Prosthesis installation and assembly

ABSTRACT

A system and method for improving installation of a prosthesis, particularly an acetabular cup. The system and method may include implementation of a constant velocity relative motion between a prosthesis and an installation site. For example, an installation system may be fixed relative to the installation site, with the prosthesis fixed into an initial position. The prosthesis is moved at constant speed (i.e., with minimal if any acceleration or applied impulses) relative to the installation site. That is, one or both of the prosthesis or the installation site may be in motion. Resistive forces to installation of a prosthesis may thus be reduced by maintaining the prosthesis constantly in motion relative to the installation site. Securing a processing/implanting tool directly to the installation site may offer advantages.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of the following five USPatent Application Numbers: U.S. application Ser. No. 15/202,434 filed 5Jul. 2016, U.S. application Ser. No. 15/362,675 filed 28 Nov. 2016, U.S.application Ser. No. 15/396,785 filed 2 Jan. 2017, U.S. application Ser.No. 15/398,996 filed 5 Jan. 2017, and U.S. application Ser. No.15/453,219 filed 8 Mar. 2017, which in turn variously directly orindirectly claim benefit of one or two provisional patent applications:U.S. Application No. 62/277,294 filed 11 Jan. 2016 and U.S. ApplicationNo. 62/373,515 filed 11 Aug. 2016, the contents of which are all herebyexpressly incorporated by reference thereto in their entireties for allpurposes. This application is also related to U.S. patent applicationSer. No. 14/584,656 (now U.S. Pat. No. 9,168,154), the contents of whichis hereby expressly incorporated by reference thereto in its entiretyfor all purposes.

FIELD OF THE INVENTION

The present invention relates generally to installation of a prosthesis,and more specifically, but not exclusively, to non-impactfulinstallation of an acetabular cup into an acetabulum during total hipreplacement procedures as well as to improvements in prosthesisplacement and positioning.

BACKGROUND OF THE INVENTION

The subject matter discussed in the background section should not beassumed to be prior art merely as a result of its mention in thebackground section. Similarly, a problem mentioned in the backgroundsection or associated with the subject matter of the background sectionshould not be assumed to have been previously recognized in the priorart. The subject matter in the background section merely representsdifferent approaches, which in and of themselves may also be inventions.

Earlier patents issued to the present applicant have described problemsassociated with prosthesis installation, for example acetabular cupplacement in total hip replacement surgery. See U.S. Pat. Nos. 9,168,154and 9,220,612, which are hereby expressly incorporated by referencethereto in their entireties for all purposes. Even though hipreplacement surgery has been one of the most successful operations, itcontinues to be plagued with a problem of inconsistent acetabular cupplacement. Cup mal-positioning is the single greatest cause of hipinstability, a major factor in polyethylene wear, osteolysis,impingement, component loosening and the need for hip revision surgery.

The incorporated U.S. Pat. No. 9,168,154, and several of its childapplications, detail a concern with conventional installation of aprosthesis in which a surgeon employs a mallet to strike a rodmechanically coupled to the prosthesis. Through a series of discrete,relatively high force strikes, the surgeon drives the prosthesis intothe living bone. There are several problems with this solution includingnon-quantified forces that may fracture the bone at the installationsite and/or may not properly seat the prosthesis within the bone.

There are several applications in the family of the incorporated USPatent Application that detail various Behzadi Medical Devices fordecreasing or minimizing impactful strikes and for improvinginstallation of a prosthesis, particularly an acetabular cup.

Earlier patents issued to the present applicant have described problemsassociated with prosthesis installation, for example acetabular cupplacement in total hip replacement surgery. See U.S. Pat. Nos. 9,168,154and 9,220,612, which are hereby expressly incorporated by referencethereto in their entireties for all purposes. Even though hipreplacement surgery has been one of the most successful operations, itcontinues to be plagued with a problem of inconsistent acetabular cupplacement. Cup mal-positioning is the single greatest cause of hipinstability, a major factor in polyethylene wear, osteolysis,impingement, component loosening and the need for hip revision surgery.

These incorporated patents explain that the process of cup implantationwith a mallet is highly unreliable and a significant cause of thisinconsistency. The patents note two specific problems associated withthe use of the mallet. First is the fact that the surgeon is unable toconsistently hit on the center point of the impaction plate, whichcauses undesirable torques and moment arms, leading to mal-alignment ofthe cup. Second, is the fact that the amount of force utilized in thisprocess is non-standardized.

In these patents there is presented a new apparatus and method of cupinsertion which uses an oscillatory motion to insert the prosthesis.Prototypes have been developed and continue to be refined, andillustrate that vibratory force may allow insertion of the prosthesiswith less force, as well, in some embodiments, of allowing simultaneouspositioning and alignment of the implant.

There are other ways of breaking down the large undesirable,torque-producing forces associated with the discrete blows of the malletinto a series of smaller, axially aligned controlled taps, which mayachieve the same result incrementally, and in a stepwise fashion tothose set forth in the incorporated patents, (with regard to, forexample, cup insertion without unintended divergence).

There are two problems that may be considered independently, though somesolutions may address both in a single solution. These problems includei) undesirable and unpredictable torques and moment arms that arerelated to the primitive method currently used by surgeons, whichinvolves manually banging the mallet on an impaction plate mated to theprosthesis and ii) non-standardized and essentially uncontrolled andunquantized amounts of force utilized in these processes. Theseunpredictable torqueing forces may also be present in assembly ofmodular prosthetic systems, especially those that employ a mallet tostrike one component onto another component during assembly.

Some of these procedures, including a manual non-quantized unpredictablestriking of an element of an implant with a mallet are present in othersituations such as assembly of a modular prosthesis. In addition to someof the related problems described herein, mallet-struck prosthesisassembly may be associated with various physiologic problems (e.g.,trunnionosis) which may limit use of surgeon-assembled modularprosthesis systems.

BRIEF SUMMARY OF THE INVENTION

Disclosed is a system and method for improving assembly of a prosthesis.The following summary of the invention is provided to facilitate anunderstanding of some of the technical features related to assembly of aprosthesis, particularly installation of a head on a trunnion neck, andis not intended to be a full description of the present invention. Afull appreciation of the various aspects of the invention can be gainedby taking the entire specification, claims, drawings, and abstract as awhole. The present invention is applicable to other prosthesis and toassembly of modular prosthesis and systems intended for installationinto a living body.

Further disclosed is a system and method for improving assembly,preparation, and installation of a prosthesis. The following summary ofthe invention is provided to facilitate an understanding of some of thetechnical features related to prosthesis assembly and installation, andis not intended to be a full description of the present invention. Afull appreciation of the various aspects of the invention can be gainedby taking the entire specification, claims, drawings, and abstract as awhole. The present invention is applicable to other prosthesis inaddition to acetabular cups, other modular prosthesis in addition toassembly of modular femoral and humeral prosthesis, and to otheralignment and navigation systems in addition to referenced light guides.

An embodiment of the present invention may include implementation of aconstant velocity relative motion between a prosthesis and aninstallation site. For example, an installation system may be fixedrelative to the installation site, with the prosthesis fixed into aninitial position. The prosthesis is moved at constant speed (i.e., withminimal if any acceleration or applied impulses) relative to theinstallation site. That is, one or both of the prosthesis or theinstallation site may be in motion. For example, a hip may be fixed inplace on an operating platform and the installation tool secured to theplatform and/or to the hip. The tool is advanced toward the hip toinsert the prosthesis into the installation site. Alternatively, or inaddition, the hip may be moved toward the installation tool, such as byfixing the installation tool above the operating platform and thenelevating the platform at a constant speed. In some applications, theinstallation tool may be part of a robotic tool to help provide accurateorientation during installation.

In an embodiment, it may be desirable to reduce forces that areresistive to the constant speed/velocity insertion. For example, asdetailed in U.S. Patent Application No. 62/319,377 filed 7 Apr. 2016 andits non-provisional conversion U.S. patent application Ser. No.15/234,927 filed 11 Aug. 2016 and a continuation-in-part thereof, U.S.patent application Ser. No. 15/406,752 filed 15 Jan. 2017, the contentsof these applications are hereby expressly incorporated by referencethereto in their entireties for all purposes, a surface modification ora surface treatment of the surface of the prosthesis engaging theinstallation site may further reduce the resistive forces. The surfacetreatment may vary, for example, and include unidirectional surfaceelements for biasing the installation or use of a paste, cream, slurry,and/or ice to provide a low resistive film.

An embodiment of the present invention may include axial alignment offorce transference, such as, for example, an axially sliding hammermoving between stops to impart a non-torqueing installation force. Thereare various ways of motivating and controlling the sliding hammer,including a magnitude of transferred force. Optional enhancements mayinclude pressure and/or sound sensors for gauging when a desired depthof implantation has occurred.

Other embodiments include adaptation of various devices for accurateassembly of modular prostheses, such as those that include a headaccurately impacted onto a trunnion taper that is part of a stem orother element of the prosthesis.

Still other embodiments include an alignment system to improve sitepreparation, such as, for example, including a projected visualreference of a desired orientation of a tool and then having thatreference marked and available for use during operation of the tool toensure that the alignment remains proper throughout its use, such asduring a reaming operation.

Further embodiments include enhancement of various tools, such as thoseused for cutting, trimming, drilling, and the like, with ultrasonicenhancement to make the device a better cutting, trimming, drilling,etc. device to enable its use with less strength and with improvedaccuracy.

An embodiment of the present invention may include a grip structure on abody of modular assembly that may provide an anchor for defining analignment axis for a trunnion of the body and a head to be installedonto the trunnion.

An embodiment of the present invention may include a head grasper thatsecures the head into an optimized assembly position relative to thealignment axis/trunnion. The optimized assembly position may includenon-relative canting and alignment with the alignment axis.

An embodiment of the present invention may include a holder that engagesa grip structure and is coupled to a head grasper. The holder may aid inreducing waste of energy used in assembly of the head onto the trunnionand it may aid in the optimized positioning of the head relative to thealignment axis/trunnion before and/or during installation of the headonto the trunnion.

An embodiment of the present invention may include use of force sourcecoupled to a head grasper/tool to generate assembly forces to installthe head onto the trunnion. The force source may deliver one or more ofa dynamic assembly force, a vibratory assembly force, a set of discreteassembly impacts, other assembly forces, and combinations thereof. Theassembly force(s) may be applied the head grasper/tool to install thehead onto the trunnion. The assembly force(s) may be constrained tooperate along the alignment axis, and may be reduced bysecuring/anchoring the body of the modular prosthesis, such as by usinga grip structure.

An embodiment of the present invention may include use of a forcesensing mechanism coupled to a head grasper/tool to measure, possibly intrue realtime (e.g., during dynamic operation of the tool to apply theassembly force(s)), the assembly force(s).

An embodiment of the present invention may include development andproduction of standards, guidelines, recommendations for an optimumforce, or force range for the assembly force(s) to achieve a desiredcold weld.

An apparatus for acting on a portion of bone, including a force transferanchor fixed to the portion of bone, the force transfer anchor includinga tool mount; and a tool, coupled to the tool mount, including anoperational end configured to interface with the portion of bone usingan interface force; wherein a portion of the interface force istransferred between the portion of bone and the tool through the forcetransfer anchor.

A method for acting on a portion of bone, including a) fixing a forcetransfer anchor to the portion of bone, the force transfer anchorincluding a tool mount; b) interfacing a tool, coupled to the tool mountand with the tool including an operational end, with the portion of boneusing an interface force; c) transferring a portion of the interfaceforce between the portion of bone and the tool through the forcetransfer anchor.

A modular prosthesis body, including a stem portion; a trunnion portioncoupled to the stem portion, the trunnion portion having an insertionprofile defining an insertion axis and further defining a pair ofopposing side faces including a first side face and a second side face;a first grip structure coupled to the first side face and disposed onthe insertion axis; and a second grip structure coupled to the secondside face and disposed on the insertion axis.

A system for assembly of a modular prosthesis including a stem portion,a trunnion portion coupled to the stem portion, the trunnion portionhaving an insertion profile defining an insertion axis and a pair ofopposing side faces defining a non-planar grip structure, and aprosthesis head configured to be installed on the trunnion portion anddefining an installation aperture complementary to the insertion profilewith the installation aperture defining an installation axis, includinga head grasper including a housing defining a cavity complementary to anouter portion of the prosthesis head with the housing having a grasperaxis extending through the cavity wherein the housing is configured tosecure the prosthesis head within the cavity and align the grasper axiswith the installation axis; wherein the head grasper includes a pair ofmating engagement structures, complementary to the grip structures, fornon-rotatingly securement of the head grasper to the trunnion portion.

An embodiment of the present invention may include a system having aportion of a living bone of a patient or other foundation, a tool foracting upon that portion of bone or foundation, and a force transferanchor that secures, constrains, and/or fixes a known relativerelationship between the tool and the portion of bone or foundation. Awide range of tools may be used for acting directly or indirectly on theportion of bone (e.g., milling, subtracting, or removing or adding bone,bone material, and/or foundation material, installing an implant,repositioning an implant, and the like). The tools may operate with manydifferent force modes relative to the portion of bone/foundation (e.g.,constant force, vibratory force, and/or a series of discrete impacts).The anchor, a controller, and/or the tool may be provided with a set ofsensors for collecting and/or assessing a set of parameters. In someimplementations, the anchor helps to reduce wasting energy applied at aninterface between the tool and the portion of bone. The anchor may aidin force transfer in some cases. An implementation of the anchor mayinclude essentially a passive static structure. In other instances, theanchor may include dynamic adjustable elements. An embodiment of thepresent invention may include a substitute for a surgical robot or otherrobotic system by providing a smart three-dimensional processing toolthat may include relativistic navigational and force sensing elements toreference processings to the patient and become relatively free of anabsolute reference system calibrated to a space or environment, such asa particular operating room. For example, use of inertial measurementunits and force sensors may allow for an embodiment that is simple andefficient.

A modular prosthesis body, including a stem portion; a trunnion portioncoupled to the stem portion, the trunnion portion having an insertionprofile defining an insertion axis and further defining a pair ofopposing side faces including a first side face and a second side face;a first grip structure coupled to the first side face and disposed onthe insertion axis; and a second grip structure coupled to the secondside face and disposed on the insertion axis.

A system for assembly of a modular prosthesis including a stem portion,a trunnion portion coupled to the stem portion, the trunnion portionhaving an insertion profile defining an insertion axis and a pair ofopposing side faces defining a non-planar grip structure, and aprosthesis head configured to be installed on the trunnion portion anddefining an installation aperture complementary to the insertion profilewith the installation aperture defining an installation axis, includinga head grasper including a housing defining a cavity complementary to anouter portion of the prosthesis head with the housing having a grasperaxis extending through the cavity wherein the housing is configured tosecure the prosthesis head within the cavity and align the grasper axiswith the installation axis; wherein the head grasper includes a pair ofmating engagement structures, complementary to the grip structures, fornon-rotatingly securement of the head grasper to the trunnion portion.

An apparatus for assembly of a modular prosthesis including a stemportion, a trunnion portion coupled to the stem portion, the trunnionportion having an insertion profile defining an insertion axis and apair of opposing side faces defining a non-planar grip structure, and aprosthesis head configured to be installed on the trunnion portion anddefining an installation aperture complementary to the insertion profilewith the installation aperture defining an installation axis, includinga clamp including a pair of mating engagement structures, complementaryto the grip structures, for non-rotatingly securement of the prosthesishead to the trunnion portion, the clamp including a force applicatorconfigured to apply a relative assembly force between the trunnionportion and to the prosthesis head to install the prosthesis head on thetrunnion portion wherein the clamp aligns the axes and wherein therelative assembly force is constrained by the clamp to be coaxial withthe axes.

Any of the embodiments described herein may be used alone or togetherwith one another in any combination. Inventions encompassed within thisspecification may also include embodiments that are only partiallymentioned or alluded to or are not mentioned or alluded to at all inthis brief summary or in the abstract. Although various embodiments ofthe invention may have been motivated by various deficiencies with theprior art, which may be discussed or alluded to in one or more places inthe specification, the embodiments of the invention do not necessarilyaddress any of these deficiencies. In other words, different embodimentsof the invention may address different deficiencies that may bediscussed in the specification. Some embodiments may only partiallyaddress some deficiencies or just one deficiency that may be discussedin the specification, and some embodiments may not address any of thesedeficiencies.

Other features, benefits, and advantages of the present invention willbe apparent upon a review of the present disclosure, including thespecification, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally-similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the present invention and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

FIG. 1-FIG. 4 illustrate a time-lapse series of constant velocityrelative motion between a prosthesis engaged by an installation systemand an installation site for the prosthesis.

FIG. 1 illustrates an initial orientation of the installation system andthe installation site;

FIG. 2 illustrates a first period after an initiation of a constantvelocity installation process;

FIG. 3 illustrates a second period after the initiation of the constantvelocity installation process;

FIG. 4 illustrates a third period after Initiation of the constantvelocity installation process in which the prosthesis has been installedwithout meaningful acceleration or impacts;

FIG. 5-FIG. 10 illustrate embodiments including installation of aprosthesis, including installation into living bone;

FIG. 5 illustrates an embodiment of the present invention for a slidingimpact device;

FIG. 6 illustrates a lengthwise cross-section of the embodimentillustrated in FIG. 5 including an attachment of a navigation device;

FIG. 7 illustrates a cockup mechanical gun embodiment, an alternativeembodiment to the sliding impact device illustrated in FIG. 5 and FIG.6;

FIG. 8 illustrates an alternative embodiment to the devices of FIG. 5-7including a robotic structure;

FIG. 9 illustrates an alternative embodiment to the devices of FIG. 5-8including a pressure sensor to provide feedback;

FIG. 10 illustrates an alternative embodiment to the feedback system ofFIG. 9 including a sound sensor to provide feedback for the embodimentsof FIG. 5-9;

FIG. 11-FIG. 14 illustrate prosthesis assembly embodiments including useof variations of the prosthesis installation embodiments of FIG. 5-FIG.10, such as may be used to reduce a risk of trunnionosis;

FIG. 11 illustrates a modular prosthesis and assembly tools;

FIG. 12 illustrates a femoral head to be assembled onto a trunnionattached to a femoral stem;

FIG. 13 illustrates alignment of an installation device with the femoralhead for properly aligned impaction onto the trunnion, such as anembodiment of FIG. 1-FIG. 6 adapted for this application;

FIG. 14 illustrates use of a modified vibratory system for assembly ofthe modular prosthesis;

FIG. 15-FIG. 16 illustrate an improvement to site preparation for aninstallation of a prosthesis;

FIG. 15 illustrates an environment in which a prosthesis is installedhighlighting problem with site preparation;

FIG. 16 illustrates an alignment system for preparation and installationof a prosthesis;

FIG. 17 illustrates modified surgical devices incorporating vibratoryenergy as at least an aid to mechanical preparation;

FIG. 18 illustrates a first embodiment for a BMD5 tool;

FIG. 19 illustrates a second embodiment for a BMD5 tool;

FIG. 20 illustrates a third embodiment for a BMD5 tool;

FIG. 21 through FIG. FIG. 37 illustrate a particular implementation of amechanical alignment system for use with an embodiment of a BMD5 tool;

FIG. 21 illustrates a side view of a prosthetic body to be mechanicallyjoined to an installable prosthetic head;

FIG. 22 and FIG. 23 illustrate a set of views of a prosthetic head to beinstalled on the prosthetic body of FIG. 21;

FIG. 22 illustrates a top view of the prosthetic head;

FIG. 23 illustrates a side view of the prosthetic head;

FIG. 24 through FIG. 27 illustrate a set of views for an anvil forimparting an assembly force to the prosthetic head;

FIG. 24 illustrates a side view of the anvil;

FIG. 25 illustrates a top view of the anvil;

FIG. 26 illustrates a bottom view of the anvil; and

FIG. 27 illustrates a sectional view through the anvil;

FIG. 28 through FIG. 32 illustrate a set of views of a two-part clampfor securing the anvil to the prosthetic head;

FIG. 28 illustrates a side view of the two-part clamp;

FIG. 29 illustrates a top view of the two-part clamp;

FIG. 30 illustrates a bottom view of the two-part clamp;

FIG. 31 illustrates a sectional view through the two-part clamp; and

FIG. 32 illustrates an enlarged view of FIG. 31;

FIG. 33 through FIG. 35 illustrate a set of views of a clamp forattachment to the prosthetic body and apply an aligned assembly force tothe prosthetic head by use of the two-part clamp;

FIG. 33 illustrates a top view of the clamp;

FIG. 34 illustrates an end view of the clamp; and

FIG. 35 illustrates a side view of the clamp;

FIG. 36 illustrates a stackup view for the mechanical alignment systemshown securing, aligning, and applying an assembly force to theprosthetic head to install it onto the prosthetic body;

FIG. 37 illustrates a representative manual torque wrench which may beused with the system illustrated in FIG. 36 to apply a predeterminedassembly force to produce a desired mechanical join of the prosthetichead onto the prosthetic body;

FIG. 38 illustrates a side view of an alternative prosthetic body to bemechanically joined to an installable prosthetic head;

FIG. 39-FIG. 42 illustrate a set of standard orthopedic bone preparationtools;

FIG. 39 illustrates a perspective view of a powered bone saw;

FIG. 40 illustrates a broach attachment for a powered reciprocating bonepreparation tool;

FIG. 41 illustrates a hand-operated reamer; and

FIG. 42 illustrates a set of bone preparation burrs;

FIG. 43 illustrates a side view of a first set of components for aconventional bone preparation process;

FIG. 44 illustrates a side view of a second set of components for athree-dimensional bone sculpting process that may be enabled by someembodiments of the present invention;

FIG. 45 illustrates a plan diagram of a smart tool robot;

FIG. 46-FIG. 49 illustrate an alternative implementation of a mechanicalalignment system;

FIG. 46 illustrates a side view of an alternative prosthetic body to bemechanically joined to an installable prosthetic head;

FIG. 47 illustrates a top view of the alternative prosthetic body ofFIG. 46;

FIG. 48 illustrates an enlarged front view of the alternative prostheticbody of FIG. 46; and

FIG. 49 illustrates an alternative clamping system for use with thealternative prosthetic body of FIG. 46;

FIG. 50-FIG. 52 illustrate an embodiment of an enhancement to theassembly systems described herein;

FIG. 50 illustrates a generic fluid injection system for use with amodular assembly system;

FIG. 51 illustrates a fluid jet system directing a fluid into a cavityof the installable prosthetic head; and

FIG. 52 illustrates an alternative fluid jet system for directing afluid into a cavity of the installable prosthetic head.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide a system and method forimproving installation of a prosthesis, particularly an acetabular cup.The following description is presented to enable one of ordinary skillin the art to make and use the invention and is provided in the contextof a patent application and its requirements.

Various modifications to the preferred embodiment and the genericprinciples and features described herein will be readily apparent tothose skilled in the art. Thus, the present invention is not intended tobe limited to the embodiment shown but is to be accorded the widestscope consistent with the principles and features described herein.

Definitions

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

The following definitions apply to some of the aspects described withrespect to some embodiments of the invention. These definitions maylikewise be expanded upon herein.

As used herein, the term “or” includes “and/or” and the term “and/or”includes any and all combinations of one or more of the associatedlisted items. Expressions such as “at least one of,” when preceding alist of elements, modify the entire list of elements and do not modifythe individual elements of the list.

As used herein, the singular terms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to an object can include multiple objects unless thecontext clearly dictates otherwise.

Also, as used in the description herein and throughout the claims thatfollow, the meaning of “in” includes “in” and “on” unless the contextclearly dictates otherwise. It will be understood that when an elementis referred to as being “on” another element, it can be directly on theother element or intervening elements may be present therebetween. Incontrast, when an element is referred to as being “directly on” anotherelement, there are no intervening elements present.

As used herein, the term “set” refers to a collection of one or moreobjects. Thus, for example, a set of objects can include a single objector multiple objects. Objects of a set also can be referred to as membersof the set. Objects of a set can be the same or different. In someinstances, objects of a set can share one or more common properties.

As used herein, the term “adjacent” refers to being near or adjoining.Adjacent objects can be spaced apart from one another or can be inactual or direct contact with one another. In some instances, adjacentobjects can be coupled to one another or can be formed integrally withone another.

As used herein, the terms “connect,” “connected,” and “connecting” referto a direct attachment or link. Connected objects have no or nosubstantial intermediary object or set of objects, as the contextindicates.

As used herein, the terms “couple,” “coupled,” and “coupling” refer toan operational connection or linking. Coupled objects can be directlyconnected to one another or can be indirectly connected to one another,such as via an intermediary set of objects.

The use of the term “about” applies to all numeric values, whether ornot explicitly indicated. This term generally refers to a range ofnumbers that one of ordinary skill in the art would consider as areasonable amount of deviation to the recited numeric values (i.e.,having the equivalent function or result). For example, this term can beconstrued as including a deviation of ±10 percent of the given numericvalue provided such a deviation does not alter the end function orresult of the value. Therefore, a value of about 1% can be construed tobe a range from 0.9% to 1.1%.

As used herein, the terms “substantially” and “substantial” refer to aconsiderable degree or extent. When used in conjunction with an event orcircumstance, the terms can refer to instances in which the event orcircumstance occurs precisely as well as instances in which the event orcircumstance occurs to a close approximation, such as accounting fortypical tolerance levels or variability of the embodiments describedherein.

As used herein, the terms “optional” and “optionally” mean that thesubsequently described event or circumstance may or may not occur andthat the description includes instances where the event or circumstanceoccurs and instances in which it does not.

As used herein, the term “size” refers to a characteristic dimension ofan object. Thus, for example, a size of an object that is spherical canrefer to a diameter of the object. In the case of an object that isnon-spherical, a size of the non-spherical object can refer to adiameter of a corresponding spherical object, where the correspondingspherical object exhibits or has a particular set of derivable ormeasurable properties that are substantially the same as those of thenon-spherical object. Thus, for example, a size of a non-sphericalobject can refer to a diameter of a corresponding spherical object thatexhibits light scattering or other properties that are substantially thesame as those of the non-spherical object. Alternatively, or inconjunction, a size of a non-spherical object can refer to an average ofvarious orthogonal dimensions of the object. Thus, for example, a sizeof an object that is a spheroidal can refer to an average of a majoraxis and a minor axis of the object. When referring to a set of objectsas having a particular size, it is contemplated that the objects canhave a distribution of sizes around the particular size. Thus, as usedherein, a size of a set of objects can refer to a typical size of adistribution of sizes, such as an average size, a median size, or a peaksize.

FIG. 1-FIG. 4 illustrate a time-lapse series of constant velocityrelative motion between a prosthesis P, engaged by an installationsystem 100, and an installation site (S) for the prosthesis P. Forpurposes of this description, prosthesis P will be described as anacetabular cup to be installed into the installation site S—a preparedcavity in an acetabulum 110 as may be part of a hip replacementprocedure.

System 100 includes a fixation apparatus 105 that fixes relative motionbetween a tool 115 mechanically communicated to prosthesis P andinstallation site S. There may be several ways to achieve thismechanical linkage, for example one or more Shantz screws fixed in thepelvic bone may secure tool 115 in the desired relative position. Asdescribed herein, installation system 100 moves prosthesis P intoplacement in installation site S with constant relative motion. Theremay be several mechanisms by which this constant relative motion isachieved. The specifics of which may impact the manner by which fixationapparatus 105 is configured and implemented. The term “constant relativemotion” is not to require that the relative motion be necessarilyuniform, though in some implementations uniform constant relative motionmay be preferred. As illustrated, system 100 places prosthesis P inmotion relative to installation site S and motion continues once started(hence constant motion) until the desired installation parameters areachieved (e.g., complete seating of prosthesis P in installation siteS).

Fixation apparatus 105, sometimes referred to herein as a force transferanchor, may be implemented in many different formats and modes. In someembodiments, apparatus 105 may consist almost exclusively of fixedstatic elements that secure, constrain, and/or fix tool 115 to a portionof bone or active foundation to be processed (e.g., acetabulum 110). Insome embodiments, apparatus 110 may include a more complex dynamicallyadjustable structure for interacting with tool 115. Some functionsdescribed herein associated with apparatus 105, bone 110, and/or tool115 may be shared, distributed, reallocated to some or others of thedevices. For example in some embodiments, tool 115 and/or apparatus 105may include force generators, such as to impart an implanting force toan implant. Apparatus 105 helps to improve the implanting (and otherprocessings) in a number of possible ways as described herein.

Tool 115 may include a robotic system or other medical device (forexample, one of the Behzadi Medical Devices (BMDs) described in anincorporated application).

FIG. 1 illustrates an initial orientation of installation system 100 andinstallation site S, FIG. 2 illustrates a first period after aninitiation of a constant velocity installation process, FIG. 3illustrates a second period after the initiation of the constantvelocity installation process, and FIG. 4 illustrates a third periodafter Initiation of the constant velocity installation process in whichprosthesis P has been installed without meaningful acceleration orimpacts.

One expression of acceleration is a change of velocity with respect totime. Thus any non-uniform constant motion may be considered to havesome acceleration as the direction or speed changes. In the presentcontext, as long as any acceleration does not produce impactful-typeforces on prosthesis P or installation site S, such an embodiment mayinclude the present invention. Preferably, the constant motion varies nomore than a predetermined amount once started, for example, relativespeed is maintained within a 25%, within 10%, within 5%, and within 1%variation.

As noted, an important consideration for some embodiments is relativemotion which may include one or both of prosthesis P and installationsite S being in motion, or being stationary, at any given time. Whichelement moves, and in which direction, is less important than that therelative motion be uniform.

It has been experimentally measured that when a cup is inserted withoutimpacts, but rather at a constant velocity, that once the movementstarts, the system may be exposed only to the coefficient of kineticfriction Uk. Some calculations suggest that the coefficient of kineticfriction for certain cup/cavity interfaces may be as much as 30% to 50%lower than the coefficient of static friction. The illustratedembodiment contemplates that the acetabular prosthetic cup be insertedinto the pelvic acetabular bone at constant velocity (withoutsignificant acceleration and without impulsive forces). Some embodimentsmay be particularly appealing when the hip replacement procedureincludes use of a robotic tool, such as MAKO robot, where the positionof the robot is very stable. Or any system where the inserting tool suchas BMD is able to be fastened to the OR table to become a rigid andstable structure.

The following is a possible representative technique. The robotic arm(or the rigid BMD tool) inserts one or more Schantz screws into pelvisaround the periphery of the acetabular rim, and in that way, stabilizesthe pelvis's position in relation to the robotic end effector arm (or astabilized BMD tool). The robotic arm (or the stabilized BMD tool) canthen push the cup into the pelvis at constant velocity without impacts,dealing only with the coefficient of kinetic friction once the motionhas started, and hence (the resistive forces of kinetic frictionregime). The resistive force (FR) that are encountered may be up to 30%to 50% lower, than an alternative where the cup would be inserted withimpulsive forces. Adding ice, slurry or other surface treatment orsurface application (see for example, U.S. Patent Application No.62/319,377 filed 7 Apr. 2016 and its non-provisional conversion U.S.patent application Ser. No. 15/234,927 filed 11 Aug. 2016 and acontinuation-in-part thereof, U.S. patent application Ser. No.15/406,752 filed 15 Jan. 2017, the contents of these applications arehereby expressly incorporated by reference thereto in their entiretiesfor all purposes) to this method of constant insertion can diminish theforce of static friction potentially by greater than 50%, makinginsertion with constant force even more attractive.

Embodiments of the present invention may include one of more solutionsto the above problems. The incorporated U.S. Pat. No. 9,168,154 includesa description of several embodiments, sometimes referred to herein as aBMD3 device, some of which illustrate a principle for breaking downlarge forces associated with the discrete blows of a mallet into aseries of small taps, which in turn perform similarly in a stepwisefashion while being more efficient and safer. The BMD3 device producesthe same displacement of the implant without the need for the largeforces from the repeated impacts from the mallet. The BMD3 device mayallow modulation of force required for cup insertion based on bonedensity, cup geometry, and surface roughness. Further, a use of the BMD3device may result in the acetabulum experiencing less stress anddeformation and the implant may experience a significantly smoothersinking pattern into the acetabulum during installation. Someembodiments of the BMD3 device may provide a superior approach to theseproblems, however, described herein are two problems that can beapproached separately and with more basic methods as an alternative to,or in addition to, a BMD3 device. An issue of undesirable torques andmoment arms is primarily related to the primitive method currently usedby surgeons, which involves manually banging the mallet on the impactionplate. The amount of force utilized in this process is alsonon-standardized and somewhat out of control.

With respect to the impaction plate and undesirable torques, anembodiment of the present invention may include a simple mechanicalsolution as an alternative to some BMD3 devices, which can be utilizedby the surgeon's hand or by a robotic machine. A direction of the impactmay be directed or focused by any number of standard techniques (e.g.,A-frame, C-arm or navigation system). Elsewhere described herein is arefinement of this process by considering directionality in the reamingprocess, in contrast to only considering it just prior to impaction.First, we propose to eliminate the undesirable torques by delivering theimpacts by a sledgehammer device or a structure (e.g., hollowcylindrical mass) that travels over a stainless rod.

FIG. 5 illustrates an embodiment of the present invention for a slidingimpact device 500, and FIG. 6 illustrates a lengthwise cross-section ofsliding impact device 500 including an attachment of a navigation device605.

Device 500 includes a moveable hammer 505 sliding axially and freelyalong a rod 510. Rod 510 includes a proximal stop 515 and distal stop520. These stops that may be integrated into rod 510 to allowtransference of force to rod 510 when hammer 505 strikes distal stop520. At a distal end 610 of rod 510, device 500 includes an attachmentsystem 615 for a prosthesis 620. For example, when prosthesis 620includes an acetabular cup having a threaded cavity 625, attachmentsystem 615 may include a complementary threaded structure that screwsinto threaded cavity 625. The illustrated design of device 500 allowsonly a perfect axial force to be imparted. The surgeon cannot deliver ablow to the edge of an impaction plate. Therefore the design of thisinstrument is in and of itself protective, eliminating a problem of“surgeon's mallet hitting on the edge of the impaction plate” or othermis-aligned force transference, and creating undesirable torques, andhence unintentional mal-alignment of prosthesis 620 from an intendedposition/orientation.

A longitudinal axis 630 extends through the ends of rod 510. Attachmentsystem 615 aligns prosthesis 620 to axis 630 when rod 510 is coupled tothreaded cavity 625. An apex of prosthesis 620 (when it generallydefines a hollow semispherical shell) supports a structure that definesthreaded cavity 625 and that structure may define a plane 635 that maybe tangent to the apex, with plane 635 about perpendicular to axis 630when rod 510 engages prosthesis 620. Operation of device 500 is designedto deliver only axial (e.g., aligned with axis 630 and thusnon-torqueing) forces to prosthesis 620. Other embodiments illustratedin FIG. 7-FIG. 10 may be similarly configured.

FIG. 7 illustrates a cockup mechanical gun 700 embodiment, analternative embodiment to the sliding impact device illustrated in FIG.5 and FIG. 6. An alternate embodiment includes cockup mechanical gun 700that uses the potential energy of a cocked up spring 705 to create anaxially aligned impaction force. Hammer 505 is drawn back and spring 705is locked until an operator actuates a trigger 710 to release spring 705and drive hammer 505 along rod 510 to strike distal stop 520 andtransfer an axially aligned impacting force to prosthesis 620.

Each pull of trigger 710 creates the same predetermined fixed unit offorce (some alternatives may provide a variably predetermined force).The surgeon cannot deliver a misaligning impact to an impaction platewith this design.

FIG. 8 illustrates an alternative robotic device 800 embodiment to thedevices of FIG. 5-7 including a robotic control structure 805. Forexample, device 500 and/or gun 700 may be mounted with robot controlstructure 805 and the co-axial impacts may be delivered mechanically bya robotic tool using pneumatic or electric energy.

FIG. 9 illustrates an alternative embodiment 900 to the devices of FIG.5-8 including a pressure sensor 905 to provide feedback duringinstallation. With respect to management of the force required for someof these tasks, it is noted that with current techniques (the use of themallet) the surgeon has no indication of how much force is beingimparted onto the implant and/or the implant site (e.g., the pelvis).Laboratory tests may be done to estimate what range of force should beutilized in certain age groups (as a rough guide) and then fashioning adevice 900, for example a modified sledgehammer 500 or cockup gun 700 toproduce just the right amount of force. Typically the surgeon may use upto 2000N to 3000N of force to impact a cup into the acetabular cavity.Also, since some embodiments cannot deliver the force in an incrementalfashion as described in association with the BMD3 device, device 900includes a stopgap mechanism. Some embodiments of the BMD3 device havealready described the application of a sensor in the body of theimpaction rod. Device 900 includes sensing system/assembly 905 embeddedin device 900, for example proximate rod 510 near distal end 610, andused to provide valuable feedback information to the surgeon. Pressuresensor 905 can let the surgeon know when the pressures seems to havemaximized, whether used for the insertion of an acetabular cup, or anyother implant including knee and shoulder implants and rods used to fixtibia and femur fractures. When pressure sensor 905 is not showing anadvance or increase in pressure readings and has plateaued, the surgeonmay determine it is time to stop operation/impacting. An indicator, forexample an alarm can go off or a red signal can show when maximal peakforces are repeatedly achieved. As noted above, the incorporated patentsdescribe a presence of a pressure sensor in an installation device, thepresence of which was designed as part of a system to characterize aninstallation pulse pattern communicated by a pulse transfer assembly.The disclosure here relates to a pressure sensor provided not tocharacterize the installation pulse pattern but to provide an in situfeedback mechanism to the surgeon as to a status of the installation,such as to reduce a risk of fracturing the installation site. Someembodiments may also employ this pressure sensor for multiple purposesincluding characterization of an applied pulse pattern such as, forexample, when the device includes automated control of an impactingengine coupled to the hammer. Other embodiments of this invention maydispose the sensor or sensor reading system within a handle or housingof the device rather than in the central rod or shaft.

FIG. 10 illustrates an alternative device 1000 embodiment to thefeedback system of FIG. 9 including a sound sensor 1005 to providefeedback for the embodiments of FIG. 5-9. Surgeons frequently use achange in pitch (sound) to gauge whether an implant (e.g., the cup) has“bottomed out” (an evaluation of a “seatedness” of the implant) anddevice 1000 includes sound sensor 1005 either attached or coupled to rod510 or otherwise disposed separately in the operating room. Sound sensorsystem/assembly 1005 may be used in lieu of, or in addition to, pressuresensor system/assembly 905 illustrated in FIG. 9.

FIG. 11-FIG. 14 illustrate prosthesis assembly embodiments including useof variations of the prosthesis installation embodiments of FIG. 5-FIG.10, such as may be used to reduce a risk of trunnionosis or for otheradvantage. FIG. 11 illustrates a modular prosthesis 1100 and assemblytool 1105. Prosthesis 1100 includes a head 1110 and a trunnion taper1115 at an end of a stem 1120 (e.g., a femoral stem for supporting aball head to fit within an acetabular cup used in a total hipreplacement procedure). During the procedure, the surgeon assemblesprosthesis 1100 by using tool 1105 which may include an impact rod 1125attached to a head coupler 1130. The surgeon uses tool 1105 to drivehead 1110 onto trunnion taper 1115 which conventionally includes a freemallet striking tool 1105. Such a procedure may be prone to the similarproblems as installation of a prosthesis into an implant site, namelyapplication of off-axis torqueing forces and an uncertainty of appliedforce and completion of assembly.

It is believed that even a 0.1 degree mal-alignment on head 1110 ontrunnion taper 1115 may lead to progressive wear and metalosis.Variations of the embodiments of devices illustrated in FIG. 5-FIG. 10and its associated content may be developed to help resolve thisproblem. In the case of “non-torqueing axiality” of forces from anassembly device, a bore of the head may define an axis, the trunniontaper may define an axis, with the assembly device aligning these axesand then applying its forces in co-axial alignment with these co-axiallyaligned axes. Such an embodiment may reduce or eliminate anyforce-responsive rotations of the head with respect to the taper as thehead is seated into position by the assembly device.

FIG. 12 illustrates a femoral head 1205, a variation of head 1110illustrated in FIG. 11, to be assembled onto trunnion taper 1115 that iscoupled to femoral stem 1120. A center dot 1210 may be placed on femoral(or humeral) head 1205 to be impacted using tool 1105.

FIG. 13 illustrates alignment of an installation device 1300, avariation of any of devices 500-1000, with femoral head 1205 forproperly aligned impaction onto trunnion taper 1115, such as anembodiment of FIG. 5-FIG. 10 adapted for this application. Suchadaptation may include, for example, an axial channel 1310 to view dot1210, and align force transference, prior to operation of hammer 505.Device 1300 includes a sledgehammer 1315 and a cock-up spring to drivesledgehammer 1315. A slot 1325 allows an operator to visualize acentering mark 1330. A spring-loading 1335 may be used to operate adevice.

Dot 1210 can be aligned with an impactor/device/gun. Once axialalignment, such as through the sight channel, has been confirmed, asledgehammer, a cockup gun, or other similar device can bang theimpactor onto femoral (humeral) head 1205 to impact it on trunnion taper1115. The co-axiality of the head and the device can be confirmedvisually (for example, through a hollow cylinder that comprises a centershaft of the device) or with a variety of electronic and laser methods.

FIG. 14 illustrates use of a modified vibratory system 1400, a variationof installation device 1300 for assembly of the modular prosthesisillustrated in FIG. 11. Alternatively to device 1300, a variation of theBMD3 device can be used to insert the femoral and humeral heads 1110onto trunnion taper 1115. For example, a version of the BMD3 devicewhere femoral head 1110 is grasped by a “vibrating gun” and introducedmethodically and incrementally onto trunnion taper 1115. Since there areno large forces being applied to the head/trunnion junction, there isessentially no possibility, or a reduced possibility, of head 1110seating onto trunnion taper 1115 in a misaligned fashion. It would bepossible to use the same technique of marking the center of head 1110and lining it up with trunnion taper 1115 and device axially beforeoperating the device.

FIG. 15-FIG. 16 illustrate an improvement to site 1500 preparation foran installation of a prosthesis 1505. FIG. 15 illustrates a site 1500 inwhich prosthesis 1505 is installed highlighting a problem with sitepreparation for a prosthesis installation procedure having variabledensity bone (line thickness/separation distance reflecting variablebone density) of acetabulum 1510. There may be an implant or other siteto be prepared having a region including dense bone and a regionincluding less dense bone, both regions present at the site. Someprocessings (e.g., reaming or other cutting) can cause a processing toolhave an altered path 1515 from an intended path deeper into the densebone. Altered path 1515 is shifted, such as away from the dense bonetowards the less dense bone.

There is a secondary problem with the process of acetabular preparationand implantation that leads to cup mal-alignment. Currently, during theprocess of acetabular reaming, surgeons make several assumptions. Onecommon assumption is that the reamer is fully seated in a cavity andsurrounded on all sides by bone. Another common assumption is that thebone that is being reamed is uniform in density. Imagine a carpenterthat is preparing to cut a piece of wood with a saw. Now imagine thatparts of this piece of wood are embedded with cement and some parts ofthe piece of wood are hollow and filled with air. The carpenter's sawwill not produce a precise cut on this object. Some parts are easy tocut and some parts are harder to cut. The saw blades skives and bends inundesirable ways. A similar phenomenon happens in acetabular preparationwith a reamer and when performing the cuts for knee replacement with asaw. With respect to the acetabulum, the side of the cavity that isincomplete (side of the reamer that is uncovered) will offer lessresistance to the reamer and therefor the reamer preferentially reamstowards the direction of the uncovering. Second, the reamer cuts thesoft bone much more easily than the dense and sclerotic bone, so thereamer moves away from the sclerotic bone and moves toward the softbone. From a machining perspective, the reaming and preparation of theacetabulum may not be concentric or precise. This maybe a significantfactor in the surgeon's inability to impact the cup in the desiredlocation

FIG. 16 illustrates an alignment system 1600 for preparation andinstallation of a prosthesis to help address/minimize this effect. Afirst step that can be taken is to include directionality into theprocess of reaming at the outset, and not just at the last step duringimpaction. Current technique allows the surgeon to ream the cuphaphazardly moving the reamer handle in all directions, being ignorantlyunaware that he is actually creating a preference for the sinking pathof the acetabular implant. Ultimately the direction in which the surgeonreams may in fact be determining the position/path of the final implant.The surgeon then impacts the cup using the traditional A-frame or any ofthe currently used intra-operative measurement techniques such asnavigation or fluoroscopy. These methods provide information about theposition of the cup either as it is being implanted or after theimplantation has occurred. None of these techniques predetermine thecup's path or function to guide the cup in the correct path.

Proposed is a method and a technique to eliminate/reduce this problem.Before the surgeon begins to ream the acetabulum, the reamer handleshould be held, with an A-frame attached, in such a way to contemplatethe final position of the reamer and hence the implant, (e.g., hold thereamer in 40 degree abduction and 20 degree anteversion reaming isstarted). This step could also be accomplished with navigation orfluoroscopy. The surgeon could, for example, immediately mark thisposition on a screen or the wall in the operating room as describedbelow and as illustrated in FIG. 16. After the anticipated position ofthe reamer is marked, the surgeon can do whatever aspect of reaming thatneeds to be done. For example the first reaming usually requiresmedialization in which the reamer is directed quite vertically to reamin to the pulvinar. Typically three or four reamings are done. First,the acetabular cavity is medialized. The other reamings function to getto the subchondral bone in the periphery of the acetabulum. One solutionmay be that after each reaming, the reamer handle be held in the finalanticipated position of the implant. In some cases it may be difficultto have an A-frame attached to every reamer and to estimate the sameposition of the reamer in the operating space accurately with theA-frame.

An alternative to that is also proposed to address this process. Forexample, at a proximal end of the reamer shaft handle will be placed afirst reference system 1605, for example a laser pointer. This laserpointer 1605 will project a spot 1610 either on a wall or on a screen1615, a known distance from the operating room table. That spot 1610 onscreen 1615 (or on the screen) is then marked with another referencesystem 1620, for example a second independent laser pointer that sits ona steady stand in the operating room. Thereafter manipulating the shafthandle so that the first reference system has the desired relationship,example co-aligned, with the second reference system, the surgeon knowsthat the device attached to the handle has the desired orientation. Sowhen the first reamer is held in the anticipated and desired finalalignment of the implant (e.g., 40 degree abduction, 20 degreeanteversion for many preferred installation angles of an acetabularcup), the laser pointer at the proximal end of the reamer handleprojects a spot on the wall or screen. That spot is marked with thesecond stationary laser, and held for the duration of the case. Allsubsequent reamings will therefore not require an A-frame to get a senseof the proper alignment and direction of the reamer. The surgeon assuresthat no matter how he moves the reamer handle in the process of reamingof the acetabulum, that the reaming finishes with the reamer handle(laser pointer) pointing to the spot on the wall/screen. In this manner,directionality is assured during the reaming process. In this way thesinking path of the actual implant is somewhat predetermined. And nomatter what final intra-operative monitoring technique is used (A-frame,C-Arm, Navigation) that the cup will likely seat/sink more closely tothe desired final position.

FIG. 17 illustrates modified surgical devices 1700 incorporatingvibratory energy as at least an aid to mechanical preparation. Alsoproposed herein is another concept to address a problem associated withnon-concentric reaming of the acetabulum caused by variable densities ofthe bone and the uncovering of the reamer. Imagine the same carpenterhas to cut through a construct that is made out of wood, air, andcement. The carpenter does not know anything about the variabledensities of this construct. There are two different saws available: onethat cuts effectively through wood only, and ineffectively through thecement. Also available is a second saw that cuts just as effectivelythrough cement as wood. Which of these saws would improve a chance ofproducing a more precise cut? Proposed is a mixing of ultrasonic energywith the standard oscillating saw and the standard reamer. In effect anyoscillating equipment used in orthopedics, including the saw, reamer,drill, and the like may be made more precise in its ability to cut andprepare bone with the addition of ultrasonic energy. This may feeldangerous and counterintuitive to some, however, the surgeon typicallyapplies a moderate amount of manual pressure to the saw and reamers,without being aware, which occasionally causes tremendous skiving,bending and eccentric reaming. An instrument that does not requires thesurgeon's manual force maybe significantly safer and as well as moreprecise and effective.

A further option includes disposition of a sensor in the shaft of theultrasonic reamers and saws so that the surgeon can ascertain when hardversus soft bone is being cut, adding a measure of safety by providing avisual numerical feedback as to the amount of pressure being utilized.This improvement (the ability to cut hard and soft bone with equalefficacy) will have tremendous implications in orthopedic surgery. Whenthe acetabular cavity is prepared more precisely, with significantlylower tolerances, especially when directionality is observed, theacetabular implant (cup) may more easily follow the intended sinkingpath.

Other applications of this concept could be very useful. Pressfit andingrowth fixation in total knee replacements in particular (as well asankle, shoulder and other joints to a lesser degree) are fraught withproblems, particularly that of inconsistent bony ingrowth and fixation.The fact that a surgeon is unable to obtain precise cuts on the bone maybe a significant factor in why the bone ingrowth technology has notgotten off the ground in joints other than the hip. The problem istypically blamed on the surgeon and his less than perfect hands. Theexperienced surgeon boasts that only he should be doing this operation(i.e.: non-cemented total knee replacement). This concept (a moreprecise saw that cuts hard and soft bone equally allowing lowertolerances) has huge potential in orthopedics, in that it can lead toelimination of the use of cement in orthopedic surgery altogether. Thiscan spark off the growth and use of bone ingrowth technology in allaspects of joint replacement surgery which can lead to tremendous timesaving in the operating room and better results for the patients.

In addition to the incorporated parent applications, embodiments of thepresent invention may include aspects of resistive force measurement,resistive force curves, and BMD tools that include force sensing, suchas described in U.S. patent application Ser. No. 15/234,782 filed 11Aug. 2016 which claims benefit of the incorporated '434 patentapplication as well as U.S. Patent Application No. 62/355,657 and U.S.Patent Application No. 62/353,024 and also described in U.S. patentapplication Ser. No. 15/284,091, all of which are hereby expresslyincorporated by reference thereto in their entireties for all purposes.

These applications include a description of a resistive force forinsertion of a hemispherical acetabular cup into an under reamed cavity.This resistive force is sometimes referred to as the FR curve, defininga “cup print” for the insertion parameters. This resistive force hasbeen described as being variable with three distinct sections. It has aprofile that may be described as an “exponential curve”. There is anidentification of an early section/part of this FR curve where poorinsertion and pull out forces exist. There is an identification of amiddle section (a sweet spot) on this FR curve where good insertion andextraction forces are achieved. And, finally, the discussion describesthat using larger forces beyond the sweet spot provide little additionalbenefit to the strength of fixation, and may increase a risk offracture. In one analogy, this FR curve may represent a dangerous peaksuch as Mount Everest having five base camps. In the discussion, thereis an observation that an orthopedic surgeon should be content to stopat base camp 3 or 4, and perhaps should not attempt to summit, whentrying to obtain press fit fixation of the cup in an under-reamedcavity. This phenomena has been described in association with BMD3 andBMD4.

There is a very serious problem in orthopedics. Some of the incorporatedpatent applications discuss trunnionosis in connection with materialregarding “BMD4” and “Intelligent Prosthesis Two”. There are fundamentalproblems related to trunnionosis in orthopedics, specifically on theinsertion of a femoral and humeral head onto the trunnion and therelated problems that have been so far described as tribocorrosion.There many who believe that the mechanism of taper corrosion is bestcharacterized as mechanically assisted crevice corrosion. Frettinginitialed crevice corrosion in tapers is a complex problem and theseverity is dependent on multiple factors. Corrosion has been associatedwith clinical complications, such as elevated metal ion levels,persistent pain, tissue damage, and early implant failure.

Regardless of the design, including shorter and slimmer trunnions andlarger heads, as well as taper angles (including positive and negativemismatch) there appears to be some universal problems with the processof head impaction onto the trunnion that have to do with “taperimpaction technique” and the “engagement of the modular taper interface”that doom the trunnion interface to failure.

Described herein are problems associated with head/trunnion impactionand possible solutions. Vibratory insertion of a prosthetic acetabularcup is extended here in that some of the same fundamental problemsassociated with mallet based impaction techniques of the prostheticacetabular cup are present here with head/trunnion impaction.

Noted below are four specific and fundamental problems with currenttechniques of head to trunnion impaction:

A) Inconsistent magnitude of force. The force is delivered by a surgeonusing a mallet. There is no standardization of magnitude of force. Thereis no guidance as to how much force needs to be delivered. The medicaldevice companies have not done In Vitro studies to determine how muchforce to deliver for a good seal. There is no a priori information as towhat type of force produces a desired “cold weld”, which appears to bewhat we need to accomplish strong fixation with no micro-motion.

B) Inconsistent direction of force. Non-axial alignment of force is thenorm for head to trunnion impaction. This produces “canting” which leadsto micro motion and corrosion.

C) Impacting against a soft object. The impact is not “elastic” but“inelastic” or plastic. The kinetic energy produced by the surgeon andthe mallet is mostly lost in a system that is inelastic. Momentum isconserved in that much of the energy produced by the surgeon and thehammer is dissipated by the spring like quality of the wholeleg/femur/thigh/prosthesis complex. But kinetic energy is not conserved,with most of the energy lost by the system described above, andtherefore, the transfer of energy from the head to trunnion interface ishighly inefficient.

D) Assuming a surgeon is able to get the right amount (magnitude) offorce delivered with the right technique (perfectly axially), How do youknow you have actually achieved a “cold weld”? How do you know when tostop application of Force? No In Vitro studies have ever been done toguide the surgeon as to how much force to apply. Also, a proper toolhave never been provided to the surgeon to accomplish this job.

The solution may include a new design with several key features.

1) A head may include a flat edge that allows it to sit flat on a table.A “head holder” may grasp the head in a ‘normal’ fashion on the flatedges. On an opposite side of the head holder a center axis point may becreated, which allows ONLY central axis application of force.

2) The force as will be described can be delivered dynamically throughcontrolled impaction as with BMD4 technique (e.g., various slide hammerconfigurations), or vibratory insertion as with BMD3 techniques or withConstant insertion (to allow the system to mostly deal with friction(e.g., a coefficient of kinetic friction Uk).

3) The prosthesis may have either indentations, holes, or ridges createdin it to allow an insertion apparatus (BMD5) to purchase and grasp theprosthesis. This is a way to avoid unnecessary loss and waste of kineticenergy.

4) A force sensor/torque wrench/strain gauge within the tool measuresthe force experienced within the tool/head/trunnion/prosthesis complex.

5) An amount (magnitude) of force required to obtain a perfect weld canbe determined in vitro. The force can be delivered with controlledimpaction, vibratory insertion, or constant insertion. The force sensormay, in some implementations, act much like a torque wrench (possibly)stopping the application of the perfectly tuned force (both magnitudeand direction) when a cold weld is obtained. Little to no dissipation offorce/energy may occur in this system. The inconsistencies that areintroduced by the surgeon and the mallet with current techniques areeliminated entirely. Since the surgeon is told in advance how much forceto deliver and given the proper tool to accomplish this job, it isimpossible to deliver less than required force. Since the tool onlyapplies perfectly axial force, no canting can occur. Since the head andtrunnion are now coupled/constrained in one physical system, wasting ofkinetic energy will reduced or eliminated. The insertion of the headonto the trunnion is now done with a technologically intelligent andreliable system.

In each of FIG. 18-FIG. 20, an embodiment of a BMD5 tool will be used tohelp assemble a modular prosthesis. This is similar to the discussion ofFIG. 11. In FIG. 11, modular prosthesis 1100 was assembled usingassembly tool 1105 while in these discussions, a BMD5 tool replaces tool1105 (with an optional modification to prosthesis 1100). Prosthesis 1100includes a head 1110 and a trunnion taper 1115 at an end of a stem 1120(e.g., a femoral stem for supporting a ball head to fit within anacetabular cup used in a total hip replacement procedure). During someembodiments of this alternative procedure, the surgeon assemblesprosthesis 1100 by using a BMD5 tool. The surgeon uses the BMD5 tool todrive, and cold weld, head 1110 onto trunnion taper 1115.

FIG. 18 illustrates a first embodiment for a BMD5 tool 1800 used incooperation with assembly of modular prosthesis 1100 to install head1110 onto trunnion taper 1115 at an end of stem 1120. Prosthesis 1100 ismodified to include a grip structure 1805 (e.g., an indentation, hole,cavity, aperture, and the like) to allow engagement of a retentionstructure (e.g., a claw, grasper, gripper, and the like—represented byG) coupled to both tool 1800 and to prosthesis 1100. Optional gripstructure 1805 may be used to reduce or eliminate wasting of kineticenergy during assembly and welding of head 1110 onto taper 1115.

BMD5 tool 1800 includes a head grasper 1810, an in-line force sensormodule 1815, a torquer 1820, and torque converter 1825. Head grasper1810 retains and aligns head 1110 into an optimum installationorientation (e.g., perpendicular/normal) to allow application of forceonly along an assembly axis 1830 joining, and aligned with, gripstructure 1805, head 1110, taper 1115, grasper 1810, module 1815 andtorque converter 1825. This alignment allows for only force applicationonly along assembly axis 1830 which prevents/reduces canting. Gripper Gis illustrated as being functionally connected to grasper 1810, butcould be mechanically communicated to another portion or component oftool 1800. This is a functional representation as there may be severalmechanical ways to implement this function, including allowing relativedisplacement of the grasper and trunnion while maintaining the desiredalignment(s).

Grasper 1810 is important in positioning (including alignment andrelative orientation) of head 1110 and trunnion 1115. Head 1110 includesan aperture, typically complementary to the taper of a mating surface oftrunnion 1115. Grasper 1810 secures head 1110 for assembly in a verysimple and efficient manner that positions, without relative canting,head 1110 and trunnion 1115.

Module 1815 may include a torque wrench/strain gauge allowing a surgeonto understand one or more forces in play, such as knowing exactly howmuch force needs to be, and is being, delivered to obtain perfect coldweld of head 1110 onto taper 1115.

Torquer 1820 may include a manual or motorized source of force ortorque, such as a torque engine which may include a rotary motor.

Torque converter 1825 transforms torque of torquer 1820 intoaxial-exclusive linear force for module 1815. When the torque engineprovides rotary force, converter 1825 may include a linear motionconverter to alter the rotary force into an axially-aligned linearforce.

In operation, femoral head 1110 may be joined to trunnion taper 1115using constant insertion. That is, head 1110 is “press-fit” with aconstant (but potentially variable) axial force. This is distinguishedfrom application of one or more discrete impacts or impulses ontograsper 1810. Constant insertion strongly implicates Uk (coefficient ofkinetic friction) which may be less than a series of discrete impactsthat more strongly implicate a coefficient of static friction. In somecases, stem 1120 is installed into bone and thereafter tool 1800 is usedto install head 1110 onto the taper of trunnion 1115 to obtain asufficient mechanical connection. Herein, that mechanical connection issometimes referred to as a “cold weld” which for purposes of thisapplication means that head 1110 and trunnion 1115 are engaged enoughthat relative micro-motion is eliminated or sufficiently reduced thatrisks of relative micro-motion are reduced below a predeterminedthreshold.

This is one aspect of the present invention, that a manufacturer ofmodular prosthetics may develop, or share, information on the forcesnecessary to produce a cold weld as noted above. Without recognition ofthe problems noted herein and a BMD5 tool to measure and/or controlassembly forces and a surgeon swinging uncalibratingly a mallet tofreely strike head 1110 and drive it onto trunnion 715, there wasinsufficient need or motivation to develop or share this type ofinformation.

FIG. 19 illustrates a second embodiment for a BMD5 tool 1900 used incooperation with assembly of modular prosthesis 1100 to install head1110 onto trunnion taper 1115 at an end of stem 1120. Tool 1900 variesfrom tool 1800 in that tool 1900 performs insertion using a vibrationprofile. The vibration profile is provided by a vibration engine 1905that may include a rotary motor 1910 coupled to a linear motionconverter 1915 to impart a vibration to head grasper 1810 (and then tohead 1110) to insert and cold weld head 1110 onto trunnion taper 1115.There are other ways to implement vibration engine 1905.

In operation, tool 1900 may join head 1110 to taper 1115 with avibratory force (implicating a blend of static and kinetic coefficientsof friction—Us and Uk), which may require less force than a series ofdiscrete/dynamic impacts onto head 1110.

FIG. 20 illustrates a third embodiment for a BMD5 tool 2000 used incooperation with assembly of modular prosthesis 1100 to install head1110 onto trunnion taper 1115 at an end of stem 1120. Tool 2000 variesfrom tool 1800 in that tool 2000 performs insertion using an impactprofile. The impact profile is provided by an impact engine 2005 thatmay include a slide hammer 2010 having an axially-limited sliding massto impart a discrete impact onto a shaft 2015 and by that mechanism tohead grasper 1810 (and then to head 1110) to insert and cold weld head1110 onto trunnion taper 1115. There are other ways to implement impactengine 2005, including manual, mechanized (e.g., robotic), andsemi-mechanized solutions.

In operation, tool 2000 may join head 1110 to taper 1115 with a seriesof one or more discrete impacts from impact engine 2005 (implicatingpredominantly/exclusively static coefficient of friction Us).

In summary BMD 5 is a tool that:

1. Advantageously modifies a femoral prosthesis in such a way to allow agrasp or engagement of the prosthesis by the BMD5 tool. This can beaccomplished in a variety of ways: A hole, dent, ridges, andindentations can be created on the prosthesis. The ability to grasp theprosthesis is important in some embodiments in that it prevents, orreduces, waste of kinetic energy.

2. The BMD5 tool may include a “head grasper” which holds the femoral orhumeral head in a perpendicular or “normal” fashion. This allows theforce of insertion/impaction to be applied perfectly axially, withoutthe risk of “canting”.

3. The BMD5 tool has a torque wrench/strain gauge/force sensor of a widevariety of possible types that measures an amount of force appliedthrough the tool/head/trunnion/prosthesis complex. The surgeon willalways know exactly how much force is being applied. The amount of forcerequired to obtain a perfect “cold weld” can be predetermined in thelaboratory. The surgeon can simply apply the force that is recommendedby the medical device company to obtain a perfect cold weld every singletime, eliminating all variability that is currently present withapplication of force with variable surgeon strengths and mallet sizes.

4. For Constant insertion, manual or motorized rotatory motion isconverted into linear motion with any linear motion converter. In asimple form, the rotatory motion of a screw/thread is converted intolinear compression. For Vibratory insertion, similarly, rotatory motionby a motor is converted into linear vibration. For Discrete Impacts asliding mass of known weight can travel over a known distance to delivera predetermined amount of force.

BMD5 may include a self-contained system that reduces any wasting ofenergy. BMD5 may allow for perfect axial delivery of force whileproviding for quantitative measurement ofapplied/communicated/transmitted force(s). So stakeholders can restassured that every step has been taken to obtain a cold weld at thetrunnion/head interface. Embodiments of BMD5 may allow a surgeon to coldweld the femoral head onto the trunnion simply, efficiently, andaccurately while minimizing risks of improper installation. Someembodiments of BMD5 may include ultrasonic press-fitting, such asdescribed in Csaba LAURENCZY et al., “ULTRASONIC PRESS-FITTING: A NEWASSEMBLY TECHNIQUE” S. Ratchev (Ed.): IPAS 2014, IFIP AICT 435, pp.22-29, 2014, hereby expressly incorporated by reference in its entiretyfor all purposes.

FIG. 21 through FIG. FIG. 37 illustrate a particular implementation of amechanical alignment system for use with an embodiment of a BMD5 tool,such as, for example, those illustrated and/or described herein. FIG. 21illustrates a side view of a prosthetic body 2100 to be mechanicallyjoined to an installable prosthetic head. Body 2100 includes a stemportion 2105 for insertion into a prepared bone and a taper portion 2110for mechanical joinder to a selected installable prosthetic head. Acenter line 2115 is defined as a central axis of taper portion 2110.Taper portion 2110 may include a two-dimensional symmetry along a lengthof center line 2115. The installable prosthetic head will include acomplementary taper cavity that may further match this two-dimensionalsymmetry over a depth of the taper cavity along a taper cavity centerline. Maintaining an alignment of these center lines as the prosthetichead is mechanically joined to taper portion 2110 may reduce, minimize,and/or eliminate canting or dangerous installation conditions that maycontribute to or exacerbate any trunnionosis related to assembly of theprosthetic head onto taper portion 2110. Body 2100 may include, as agrip structure, a non-traditional through-hole 2120 centered on centerline 2115 proximate taper portion 2110.

In some embodiments, grip structure 2120 may not be a through hole butmay include, for example, laterally opposed divots with each centered oncenter line 2115. In other embodiments, the grip structure may include aconventional non-center line aligned element 2125. An adaptor, jig, orengagement system cooperating with element 2125 may provide apredetermined offset to align such other assembly components with centerline 2115.

FIG. 22 and FIG. 23 illustrate a set of views of a prosthetic head 2200to be installed on taper portion 2110 of prosthetic body 2100. FIG. 22illustrates a top view of prosthetic head 2200 and FIG. 23 illustrates aside view of prosthetic head 2200. Prosthetic head 2200 defines an outerspherical surface 2205, at least a hemisphere, and further includes aplanar face 2310, offset from but generally parallel to a diameter ofthe spherical portion of head 2200. An aperture is defined in planarface 2310, this aperture provides an opening into a taper cavity 2215disposed within prosthetic head 2200. Taper cavity 2215 is designed tomate and engage with taper portion 2110 and in this sense is referred toherein as being complementary. Taper cavity 2215 also defines a tapercavity center line 2220 also having a two-dimensional symmetry along adepth of taper cavity 2215, and in some cases taper cavity center line2220 is perpendicular to planar face 2310. An optional feature includesa marking, for example, a laser etch or other patterning modality, thatapplies a visible set of “cross hairs” 2225 centered on taper cavitycenter line 2220.

A goal of the supporting structures of some embodiments of the presentinvention may include configuring alignment of center line 2115 withcenter line 2220, maintaining that alignment while taper portion 2110 ismechanically joined with taper cavity 2215, and in some cases monitoringa magnitude of applied assembly forces to achieve a desired mechanicaljoin (e.g., a cold weld or the like).

While the cross sections along a length of the center lines for bothtaper portion 2110 and taper cavity 2215 are circular, other crosssectional shapes may be employed without departing from the presentinvention.

FIG. 24 through FIG. 27 illustrate a set of views for an anvil 2400intended to impart an assembly force to prosthetic head 2200 relative toprosthetic body 2100. FIG. 24 illustrates a side view of anvil 2400,FIG. 25 illustrates a top view of anvil 2400, FIG. 26 illustrates abottom view of anvil 2400, and FIG. 27 illustrates a sectional viewthrough anvil 2400 at A-A of FIG. 24. Anvil 2400 includes a solid body2405 having a circumferential channel 2410 extending completely aroundan outside of a lateral sidewall of body 2405. Body 2405 includes a topface 2415 and a bottom face 2420 spaced apart from top face 2415 by thesidewall. A spherical sectional depression 2425 is defined in top face2415. Depression 2425 is complementary to outer spherical surface 2205.Depression 2425 has a depth to position the planar face of prosthetichead 2200 into a predetermined relationship with top face 2415. In someinstances, bottom face 2420 may define a tap or aperture 2605 that iscentered at a longitudinal axis 2705 of body 2405 that extends throughtop face 2415 and bottom face 2420 and automatically aligns with tapercavity center line 2220 when prosthetic head 2200 is installed intomating depression 2425. Bottom surface 2420 supports an anvil axisinteraction structure, such as tap or aperture 2605 and/or otherstructure, which may be used for visual confirmation of axial alignmentwith indicia 2220, or may be used for receipt of a force applicator, orsome additional or other interaction with anvil 2400.

In some embodiments, aperture 2605, the optional structure, may extendfrom bottom surface 2420 into depression 2425. When so provided, andwhen prosthetic head is further provided with optional cross hairs 2225,it is possible to confirm alignment of axis 2705 with center line 2220when cross hairs 2225 are visible in aperture 2605.

FIG. 28 through FIG. 32 illustrate a set of views of a multi-partadaptor 2800 for securing anvil 2400 to prosthetic head 2200. FIG. 28illustrates a side view of multi-part adaptor 2800, FIG. 29 illustratesa top view of multi-part adaptor 2800, FIG. 30 illustrates a bottom viewof multi-part adaptor 2800, FIG. 31 illustrates a sectional view throughmulti-part adaptor 2800, and FIG. 32 illustrates an enlarged view ofFIG. 31. As illustrated, multi-part adaptor 2800 includes twohalf-shells (half-shell 2805 and half-shell 2810, each half-shell amirror image of the other) though other configurations may provide for adifferent number of parts.

These are half-shells because they each include a rigid exterior wallcooperatively defining an interior cavity 3105 that is sized andconfigured to secure and hold prosthetic head 2200 within depression2424 of anvil 2400 while center line 2225 is aligned with axis 2705.Adaptor 2800 defines a top face 2815 and a bottom opening 2820. Top face2815 defines an aperture 2905 for receipt of taper portion 2110 whenprosthetic head 2200 is installed into depression 2424 of anvil 2400 andboth head 2200 and anvil 2400 are installed into cavity 3105.

Interior portions of the walls of adaptor 2800 further define aninterior circumferential ledge 3110 that is designed to mate tocircumferential channel 2410 when adaptor 2800 secures anvil 2400 andhead 2200. A distance from ledge 3110 to top face 2815 is based upon aheight of the planar face of head 2200 above depression 2424 when head2200 is installed in anvil 2400 with axis 2705 aligned with center line2225. By matching the distance to the height, top face 2815 willautomatically align center line 2225 with axis 2705 when the half-shellsare closed down on head 2200 and anvil 2400.

As further detailed in the enlarged view of adaptor 2800 in FIG. 32,aperture 2905 in top face 2815 may be formed with sloped edges to matchan angle of taper portion 2110.

As illustrated, adaptor 2800 may be configured to a particular one sizeof prosthetic head 2200. When a differently sized prosthetic head 2200is to be installed on taper portion 2110, a different adaptor 2800 maybe used and in some embodiments, this is the only modification that needbe made to the system to accommodate differently sized heads. Similarly,with proper attendance to the configuration options, different sizedbodies may be matched to different sized heads by only varying adaptor2800 in appropriate fashion.

FIG. 33 through FIG. 35 illustrate a set of views of a clamp 3300 forattachment to prosthetic body 2100 and apply an aligned assembly forceto prosthetic head 2200 by use of the multi-part adaptor 2800. FIG. 33illustrates a top view of clamp 3300, FIG. 34 illustrates an end view ofclamp 3300, and FIG. 35 illustrates a side view of clamp 3300. Clamp3300 includes a “U-shaped” body 3305 having a first leg 3310, a secondleg 3315, and a bridge 3320 coupled to each leg. A distal end of eachleg defines an aperture 3325 that are aligned with each other.

Bridge 3320 defines a force application structure 3330 for allowing anassembly force to be transferred from outside of clamp 3300 to alocation disposed between the legs. In FIG. 34, structure 3330 includesa tapped/threaded interior surface to allow a complementary threadedbolt to pass into the location. FIG. 35 illustrates that in thisimplementation, structure 3330 is aligned (e.g., coplanar) withapertures 3325.

As noted herein, there may be many different types of assembly forcesused and therefore the transfer structure may need to be adaptedaccordingly to accommodate the particular assembly force in use. Forexample, in some cases, a simple aperture may be used and other casesclamp 3300 may be part of a robotic system, among other variations.

FIG. 36 illustrates a stackup view for a mechanical alignment system3600 shown securing, aligning, and applying an assembly force F toprosthetic head 2200 to install it onto prosthetic taper 2110. A pin3605 is illustrated that is passed through aligned apertures 3325 andstructure 2120 which aligns to center line 2115 and secures thecomponents to prosthetic body 2100.

A representative assembly force F is applied by use of a screw 3610threaded through structure 3330. A pad 3615 at a distal end of screw3610 contacts anvil 2400 and helps to distribute assembly force F whenapplied against the assembly including head 2200, anvil 2400, andadaptor 2800. Assembly force F, applied on a force application axis 3620is automatically aligned with center line 2115 as is the taper cavity ofhead 2200.

As screw 3610 is rotated, it is advanced into the space between the legsof clamp 3300 which transfers assembly force F onto the assembly thatincludes prosthetic head 2200. Assembly force F causes head 2200 andtaper portion 2110 to join together without tilting, canting, oroff-axis torqueing impacts, such as is often applied from a mallet.

During joinder of head 2200 and taper portion 2110, as assembly force Fincreases at some point a desired mechanical join is achieved. In somecases, this mechanical join may include a desired cold weld with reducedrisk of trunnionosis. As noted herein, in some cases it may be desirableto continue to increase assembly force F until a desired assembly forceprofile is achieved.

FIG. 37 illustrates a representative manual torque wrench 3700 which maybe used with the system illustrated in FIG. 36 to apply a predeterminedassembly force, or assembly force profile (e.g., Force F) to produce adesired mechanical join of prosthetic head 2200 onto prosthetic body2100.

FIG. 38 illustrates a side view of an alternative prosthetic body 3800to be mechanically joined to installable prosthetic head 2200. Body 3800includes a stem portion 3805 for insertion into a prepared bone and amodular taper portion 3810 for mechanical joinder to selectedinstallable prosthetic head 2200. A center line 2115 is defined as acentral axis of modular taper portion 2110. Modular taper portion 2110may include a two-dimensional symmetry along a length of center line2115. Installable prosthetic head 2200 will include a complementarytaper cavity that may further match this two-dimensional symmetry over adepth of the taper cavity along a taper cavity center line. Maintainingan alignment of these center lines as prosthetic head 2200 ismechanically joined to taper portion 2110 may reduce, minimize, and/oreliminate canting or dangerous installation conditions that maycontribute to or exacerbate any trunnionosis or tribocorrosion relatedto assembly of prosthetic head 2200 onto taper portion 2110 andinstallation of modular trunnion 3810 into body 3800. Body 3800 mayinclude, as a grip structure, a non-traditional through-hole 3815 (ordetent/depression/extension/pin or other physical structure centered oncenter line 2115.

In some embodiments, grip structure 3815 may not be a through hole oncenter line 2115 but may include, for example, laterally opposed divotswith each centered on center line 2115. In other embodiments, the gripstructure may include a conventional non-center line aligned element2125 which may have optionally been provided for removal of body 3800when installed. An adaptor, jig, or engagement system cooperating withelement 2125 may provide a predetermined offset to align such otherassembly components with center line 2115.

Differences between body 3800 as compared to body 2100 may include oneor more of the following possible elements. Illustrated in FIG. 38 isuse of modular taper portion 3810 in which the modular prosthesis mayinclude three interchangeable elements: stem, trunnion taper, and head(FIG. 38) as compared to two interchangeable elements: integratedstem/trunnion and head (FIG. 21).

Modular trunnion taper 3810 may be a separate element that includestaper portion 3810 coupled to a trunnion extension 3820. Trunnionextension 3820 is designed to be inserted into and received and securedby a complementary trunnion extension channel defined in stem 3805.Trunnion extension 3820 may also include a center line and may also usean extension taper for mechanical joinder of modular trunnion taper ontostem 3805. The system described herein may be used to center and axiallyinstall modular trunnion taper 3810 into the channel of stem 3805.Modular trunnion taper 3810 may optionally include a visible indiciamarking a center line of trunnion extension 3820 to aid innon-tilting/non-canting installation of extension 3820 into the channelof stem 3805.

As illustrated, a centerline of extension 3420 is aligned with centerline 1715 of modular trunnion portion 3410 and grip structure 2120 orgrip structure 3815 may be used for installation of both elements(extension 3820 into the channel and then head 2200 onto modulartrunnion portion 3810 thereafter). Alternatively, extension 3820 may beprovided with a grip structure and head 2200 first installed ontomodular trunnion portion 3810 and then the subassembly of head 2200 andmodular trunnion portion 3810 thereafter installed onto stem 3805.

In some cases, a more complex assembly system results when a center lineof extension 3820 is not aligned with center line 2115 of modulartrunnion portion 3810 but the system described herein may be suitablyadapted for assembly, including but not limited to multiple gripstructures aligned with each center line (or variable jigs for properoffset at each stage of assembly).

There are a number of functions may be achieved by the assembly systemincluding establishment and maintenance of alignment of all axes duringassembly, reduce inefficient use of assembly forces, and provide formeasure of assembly force(s) used during assembly.

Reduction of inefficient energy usage may be achieved by the mechanicalcoupling of the two elements being joined (e.g., stem and head, stem andmodular trunnion, head and modular trunnion, subassembly of head/modulartaper and stem, and the like). This is contrasted to a conventionalapproach of installing a stem into a patient bone and then using amallet to hammer a head onto the stem—some of the kinetic energy isabsorbed by the bone, body portion, operating table, and the like. Bymechanically linking one portion to the other during the assembly, thisloss of assembly energy is reduced or eliminated.

Another function of establishment and maintenance of axial alignment maybe achieved by awareness of axes and ensuring that these axes arealigned as assembly forces are applied. As noted, the variousstructures, systems, and processes described herein aid in theestablishment and confirmation, in some cases this is doneautomatically, of alignment before and during application of forceassembly. The definition and establishment of predetermined centerline(s), fixing structures to these center line(s), and ensuring thatappropriate axes are aligned to the appropriate center line(s) duringapplication of the assembly force(s).

Body 3800 of FIG. 38 differs from body 2100 of FIG. 21 not only from thedescription of the optional modularity of the trunnion portion, butfurther illustration of an optional use of a non-circular gripstructure. Grip structure 2120, as implemented in FIG. 36, allows clamp3300 to rotate about pin 3605 because pin 3605 may act as axle or pivot.In some cases, such as when there is some misalignment of an applicationof force to the center line(s) of center line 2115. This misalignmentmay contribute an undesired tilting, canting, or other non-alignedassembly.

Body 3800 provides grip structure 3815 with an irregular perimeter thatinhibits or prevents rotation. As illustrated, grip structure 3815includes a polygon (e.g., an N-sided regular polygon, N an element of aninteger set {3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more} of sides, N=3 forin FIG. 38. The irregular perimeter need not be a regular polygon, itmay be an irregular polygon. In other instances, it may be an oval,oblong, ovoid, or other non-circular perimeter.

In other implementations, anti-rotation may be provided by use of two ormore grip structures that are spaced apart from any other gripstructure, when the multiple grip structures are used concurrentlyduring application of an assembly force. One or both of these gripstructures may include a circular perimeter.

As illustrated, the prosthesis bodies (body 2100 and body 3800) areillustrated for use in shoulder (e.g., humerus) and hip (e.g., femur)modular prosthetic assemblies. There are other modular prosthesessystems in which there are mechanical joinders of multiple prosthesiscomponents. Whenever there are two prosthesis components that must bemechanically joined together, some embodiments of the present inventionmay be applied to axial assembly of these other modular prosthesissystems. For example there are modular systems for knee, ankle, wristand other joints and skeletal systems that may benefit from use of thepresent invention when a body (not limited to a stem or the like) isjoined to another modular component.

Regarding ultrasonic assisted bone preparation in orthopedics, there isa problem with preparation of bone in joint replacement: theseprocedures are typically performed using conventional orthopedicequipment such as 1) saw, 2) broach, 3) reamer, and 4) burr.

FIG. 39-FIG. 42 illustrate a set of standard orthopedic bone preparationtools, FIG. 39 illustrates a perspective view of a powered bone saw3900, FIG. 40 illustrates a broach attachment 4000 for a poweredreciprocating bone preparation tool (a surface including a set ofcutting, abrading, bone removing structures), FIG. 41 illustrates ahand-operated reamer 4100, and FIG. 42 illustrates a set of bonepreparation burrs 4200. Conventionally, these tools include an operatingmotion with one degree of freedom (e.g., saw 3900 has a blade that moveslaterally, broach attachment 4000 reciprocates longitudinally, reamer4100 and burrs of set of burrs 4200 each rotate about a longitudinalaxis).

As noted below, these bone preparation tools may be enhanced by addingan additional vibratory motion component, preferably but not necessarilyrequired, that is “orthogonal” to the conventional cutting motion. Saw3900 includes a laterally reciprocating cutting blade that may beultrasonically enhanced by an additional ultrasonic vibratory motion inone of the other five degrees of motion (e.g., vertical, longitudinal,or vibratory rotations of the blade such as pitch, yaw, and/or roll).Similarly each of the conventional tools has a primary mode of freedomof motion for the bone processing and an enhancement may be made byadding an additional vibratory motion in one or more other modes offreedom. Embodiments of the present invention may include an additionalvibratory motion, in the primary mode and/or the additional mode(s) thatmay be imperceptible visually (a very small amplitude and/or very fastabout or beyond 20,000 hertz).

During bone preparation, two types of bony surfaces are generallyencountered which include flat surfaces and contained surfaces. For theflat surfaces, seen in knee replacement, (end of the femur or the top ofthe tibia) saw 3900 is used to cut the bone. For the contained surfaces(such as the acetabulum and the proximal femur), as in hip replacementsurgery, broach attachment 4000 or reamer 4100 is used to prepare thebone.

A problem with all of these techniques is that the density of the boneis not uniform between patients and even within the same compartment orjoint of a single patient. The bone can be very soft or very hard andvary from region to region. With hard bone, saw 3900 may “skive” whichcauses an uneven cut surface and which minimizes that chance ofsuccessful “porous ingrowth”. This fact may be a principle reason thatcement is still used in knee replacement. For the contained bonecavities such as the acetabulum and proximal femur a “goldilocks”situation exists. During preparation, a surgeon may desire to know howwith confidence to prepare the bone to provide just the right amount ofcompressive (fit). Not too loose and not too tight. Too loose leads toloosening and potential infection of the prosthesis. Too tight leads toeither poor seating (which can lead to failure of fixation) or fracture(which leads to loss of press fit fixation and loosening).

Current art does not provide a reliable and consistent tool or methodfor the orthopedic surgeon to reliably prepare a (variable density bone)in order to obtain a “perfect” fit for the prosthesis, whether the boneis flat as in the tibia in knee replacement or contained as in theacetabulum in hip replacement.

For contained cavities such as the acetabulum, U.S. patent applicationSer. No. 15/234,782 filed 11 Aug. 2016 (all the content hereby expresslyincorporated by reference thereto in its entirety) described a basicestimation of the compressive forces involved in bone. This was named acompressive force and developed an FR curve where FR is related Fn. Us;where Fn represents the normal forces and Us represents the coefficientof static friction. Vis a vis Hooke's law the FR=K. x. Us. Where Krepresents the material properties of bone (the spring like quality ofbone) and x represents the amount of under-reaming of bone compared toan oversized prosthesis intended for press fit.

This current discussion mostly concerns itself with the variable “x”which represents the spring like quality of bone. In Hooke's law F=k. x;k is the spring's constant and x is amount of stretch placed on thespring. In orthopedic bone preparation k is represented by the materialproperties of bone and x is represented by the difference between thediameters of the prepared bone versus the prosthesis to be press fit.

As we have stated in the earlier papers, the surgeon and industry bothappear to have a poor understanding of the basic science of theprosthesis/bone cavity interaction. It is believed that x can be moretightly and precisely machined to give a better tuning of the bone,which is to accept an oversized prosthesis.

BMD3 bidirectional vibratory tool for preparation of bone, and inparticular the acetabular cavity: The use of a Acetabular Broach: a newidea. BMD3 bi-directional vibratory tool can be used for preparation ofbone (any cavity of bone that needs to be prepared for application of aprosthesis, but especially the acetabulum, as well as the proximalfemur, proximal tibia, proximal humerus, and any other long bone in thebody that receives a prosthesis). With regards to the acetabulum, unlikethe other bones discussed above, this structure has never before beenprepared with a broach, but rather always prepared with a hemispherical“cheese grater type” reamers that rotates in one direction (forward). Weare proposing that the acetabulum be prepared with a broach using one ofthe two degrees of freedom for oscillation

(1. Longitudinal and 2. rotational), utilizing a bidirectional BMDvibratory tool. The outer surface of this broach will very closelyresemble the rough surface of the prosthesis, with high coefficient ofstatic friction. We have seen this method in action in our experiments,particularly at higher frequencies of around 300 hertz, and believe thatthis method of acetabular preparation will provide a cut surface that ismuch more precise and conferring the ability to produce lowertolerances. This method may also allow preparation of acetabular cavityin “half” sizes. Currently the cavity is reamed in 1 mm intervals. Itmay be much easier to prepare the acetabulum with ½ mm interval broachesthan ½ mm reamers. Half size broaching may dramatically improve theability of the surgeon to cut and prepare the acetabular precisely andat lower tolerances.

For purposes of review we recall the equation FR=K. x. Us. Where x isrepresents the amount of under reaming and the shape of the cup beinginserted.

X is controlled by the amount of under or over reaming of theacetabulum. In the past when the surfaces of the cup were not as rough(lower coefficient of static friction, i.e. Zimmer Fiber Metal cup),surgeons used to under ream by 2 mm. Now most companies recommend underreaming by 1 mm, since the surfaces of most cups are much more roughwith better porosity characteristics that allow better and quicker bonyingrowth. Sometimes when the surgeon has difficulty seating the cup,he/she reams line to line, and describes this action as “touching up therim”. This action however, many times, eliminates the compressivequality of the acetabulum by decreasing the value of x towards zero.This issue brings attention to the problem that we have described whichis that the surgeon does not have anything but a most basicunderstanding of the spring like qualities of bone. If he/she is canunderstand the basic science involved in this system, he can then usethe proper tools to appropriately fine tune the pelvis for a good pressfit fixation, without fear of under seating or fracture. There is a hugemarket need for better tools to prepare (fine tune) the acetabulum, forgood press fit fixation.

Current techniques utilize ‘cheese grater type’ hemispherical reamers toprepare the bed of the acetabulum. As discussed in our BMD4 paper thequality of acetabular bone can be drastically different between patientsand even within the same patient, particularly at different locationsaround the acetabular fossa. Some parts of the bone are soft, and someare hard. Current cheese grater hemispherical reamers come in 1 mmintervals. This creates two specific problems: 1. The current acetabularreamers in 1 mm intervals for preparation of the acetabular bone do notprovide the ability to precisely machine the acetabulum, and obtainlower tolerances, and therefore proper tuning of the pelvic bone. 2. Nomethod exists to cut hard and soft bone with the same level ofeffectiveness, i.e.: hard bone always pushes the reamers towards thesoft bone which ends up being chewed up more, and in that sense, aperfect hemisphere is not created with current cheese grater reamingtechniques. We therefore are proposing two distinct and separatesolutions which we believe can remedy this problem of poor qualityacetabular preparation.

1. The creation of half reamers. The production and use of half reamersgives the surgeon the ability to ream up or down by half millimeters.Which gives him/her the ability to fine tune x more precisely, andtherefore FR more precisely. This basically gives the surgeon a betterset of tuning forks to obtain better tension for the acetabulum andutilize its viscoelastic properties to his/her advantage to obtain abetter press fit fixation.

2. Ultrasonic assisted reaming or broaching: Lastly, we believe thatthere is some room for creating a better cutting tool by addingultrasonic energy to either the acetabular broach described above or theacetabular half reamers described above to create an ultrasonic assistedreaming or broaching of the acetabulum for obtaining a more precise cutand at a lower tolerance. We believe this is a new and novel idea thatcan be considered for preparation of the acetabulum for obtaining bettertension of the pelvis for application of an acetabular prosthesis.

The following further elaborates upon ultrasonic assisted preparing,milling, burring, sawing, broaching, reaming, and the like in order toobtain a more precise and efficient process of bone preparation in jointreplacement surgery.

Another important advance in orthopedics is the use of robotics in theoperating room. Sensors and computer-controlled electromechanicaldevices are integrated into a robot with a haptic sense, where roboticmanipulators now have a complete spatial sense of the patient's bone inthe operating room, sometimes to within a half millimeter of accuracy.

Currently robots such as the Stryker Mako robot use a standard rotatingburr, reamer or a standard saw to prepare the bone for application of aknee or hip prosthesis. The term “robot” has a special meaning in thecontext of preparation of live bone in a living patient. Currently it isimpermissible to automate any cutting of the live bone. Robot in thissense operates as a realtime constraint that provides haptic feedback tothe surgeon during use when certain movements of the processing tool areoutside predetermined limits.

An advantage of the robot is that it is helps in processing bone towithin less than half a millimeter. This means that the surgeon cannoteasily push the burr, reamer or saw out of the allowed haptic plane. Ina sense, with the robot, the cutting tool is in safer hands. Thesestandard tools (burr, saw, reamer) provide no particular advantage forthe robotic system, that is, the conventional robotic system usesconventional tools with the constraint haptic system. A disadvantage ofthe robot is that the process of cutting bone with a burr, saw andreamers are very inefficient (slow) especially in hard sclerotic bone.The robot is also very a bulky piece of equipment that adds time to theoperation. Mako or other robotic knee surgeries have been somewhatadopted in the uni-compartmental knee replacement procedures (less than10% of surgeons), and is currently being investigated for use in totalknee replacement (Not yet in general markets). The use of the Mako robotin hip replacement however, has shown a very poor adoption rate; lessthan 0.01% of surgeons have used the Mako robot for hip replacement.Some of the weakness of this robotic procedure is in the process of 1.bone preparation and 2. the actual insertion of the prosthesis intobone.

Earlier tools have addressed tools for installing an acetabular cup intothe bony cavity with either “vibratory-BMD3” technique or “discreteimpact-BMD4” technique. These solutions are believed to largelyeliminate the problems associated with insertion of the prosthesis,providing the ability not only to insert but also to position theprosthesis in proper alignment. Other tools have dealt with manipulatingthe value of Us, coefficient of static friction, during a process ofinsertion.

An embodiment of the present invention may include a better job ofpreparation of bone. In effect, some embodiments provide a tool orprocess that more precisely manipulates the value of x in the formula:FR=K. x. Us. A goal of some embodiments of the present invention is toobtain lower (tighter tolerances) and do it more quickly, with differenttools and methods such as disclosed herein.

An embodiment of the present invention may include bone preparationusing robotic surgery through use of haptic control and management toprovide an unprecedented level of safety and accuracy coupled withmodified equipment that more efficiently prepares in-patient bone whileoffering novel solutions for bone preparation. In some of theseimplementations the robotic haptic feedback may be exploited by additionand utilization of a more powerful and efficient bone cuttingtool/method never before used or contemplated in orthopedics as it wouldhave been too easy to mis-process a bone portion.

Ultrasonic motion may be added to traditional bone processing tools(e.g., to the tools of FIG. 39-FIG. 42) to offer effectivenon-traditional bone processing tools. This addition of ultrasonicenergy to standard cutting, milling, reaming, burring and broachingtechniques can be used to provide (methods and tools) in orthopedicsurgery to remove bone more effectively with a (higher material removalrate) MMR and with significantly less force, and therefore moreefficiency.

Specifically, in hip replacement surgery the traditional reamer, broachor burr can each be equipped with an ultrasonic transducer to provide anadditional ultrasonic vibratory motion (e.g., longitudinal axialultrasonic vibration). These new cutting methods can then beincorporated within, or in association with, a robot that only allowsoperation of the tool within safe haptic zones. This ultrasonic roboticcutting tool is therefore more powerful, fast and precise. It would cuthard and soft bone with equal efficiency. Additionally, the roboticoperation of an ultrasonic assisted cutting tool is safe, in that therobot does not allow operation of the tool outside of the haptic safeplanes.

For example, a Mako robot may be equipped with a rotatory ultrasonicbone preparation tool, operating a bone processing tool (such as singlemetal-bonded diamond abrasive burr) that is ultrasonically vibrated, forexample in the axial direction while the burr is rotated about thisaxis. This tool can prepare both the proximal femur and acetabulumquickly with extreme precise. This tool and method therefore does awaywith the standard manual broaching techniques used for femoralpreparation and the standard reaming techniques used for acetabularpreparation.

An implementation of this system of a constrained ultrasonic vibrationof a bone processing tool such as a rotating burr enables athree-dimensional bone-sculpting tool or a smart tool robot. Thesculpting tool and smart tool robot may allow a surgeon to accurately,quickly, and safely provide non-planar contours when cutting bones asfurther described below while also potentially replacing all theconventional preparation tools of FIG. 39-FIG. 42.

The addition of the ultrasonic bone preparation tool to a robot makesthe system a truly efficient and precise tool. The surgeon can sculptthe surfaces of the bone, for example a femur, tibia or an acetabulumand the like, and in some implementations any tissue may be sculptedwith the sculpting tool, with high degree of accuracy and speed.

With current tools, it would take too much time to perform such bonepreparation with a burr, making the operation extremely slow and addingrisk to the patient and is therefore not performed. Some implementationsinclude an addition of an improved bone processing tool to anyhaptically constrained system will make the preparation of bone forjoint replacement easy, fast and efficient, ultimately delivering on thepromise of a better, faster and more precise operation.

With respect to knee and shoulder replacement, some of the bone surfacesare flat which have led to prosthetic designs that have a flatundersurfaces, and the decision to prepare these bones with a saw. Oneconcept is to add ultrasonic axial vibrations to the saw for a moreeffective cut.

Ultrasonic enhancement may be added to all current bone removaltechniques in orthopedics, including the burr, saw, reamer, and thebroach, making all of these bone preparation tools more effective.

In some instances, use of the same burr described above (e.g., arotating tool with metal-bonded diamond abrasives that is ultrasonicallyvibrated in the axial direction) to prepare surfaces of the tibia, femurand the glenoid in the shoulder for mating to an implant surface. Oneimportant benefit of use of such a burr is that the surgeon and thesmart tool robot can now very quickly and effectively machine thesemating surfaces any way desired, potentially introducing waves andcontours that can match the undersurface of the prosthesis (which itselfhas been created with waves and contours for additional stability.Portions of the tibia and the glenoid in the shoulder are flat bonesthat do not have inherent stability. These bones are prepared in such away to accept a prosthesis with a flat surface. With the advent ofhigh-power 3D bone sculpting, 3D printing, and smart tool hapticconstraint, the sculpting/smart tool system may create prostheses thathave waves and contours on their bottom surface to enhance stabilitywhen mated. For example, a bone surface may be 3D sculpted/contoured anda prosthesis produced to match the profile or a preformed contouredprosthesis may be provided with a non-flat profile and the mating bonesurface may be sculpted/contoured to match the preformed non-flatprosthesis mating surface, particularly for the “flat ended” bone andthe associated prostheses. These contouring profiles for bone andimplant mating surfaces are not limited to “flat ended” bones and mayhave benefit in other implants or bone mating surface.

These changes can enhance the initial fixation of the prosthesis to boneby creating a contact surface areas which are more resistant to shearforces. This may provide a specific advantage for the tibial componentin knee and the glenoid component in shoulder replacement surgery. Theseprostheses generally have flat undersurfaces and are less inherentlystable. They can be made significantly more stable with the suggestedchanges in the method of bone preparation and prosthesis fabrication.

FIG. 43 illustrates a side view of a first set of components 4300 for aconventional bone preparation process and FIG. 44 illustrates a sideview of a second set of components 4400 for a three-dimensional bonesculpting process that may be enabled by some embodiments of the presentinvention.

Components 4300 include a bone B (e.g., a tibia) having a flat end 4305.Flat end 4305 is typically removed by a conventional version of saw3900, to allow an implant 4310 to be installed. In the conventionalprocess, bone B is prepared having a flat/planar bone mating surface4315 which matches a flat/planar implant mating surface 4320 of implant4310. As noted, the pair of mated surfaces may exhibit instability,especially with lateral shear loading.

Components of 4400 include bone B that has been prepared differently byremoving flat end 4305 using an orthopedic sculpting system as describedherein. The sculpting system enables use of an implant 4405 thatincludes a contoured (non-flat/planar) implant mating surface 4410. Abone mating surface 4415 produced by the orthopedic sculpting system iscontoured to match/complement implant mating surface 4410. Components4400 may include a preformed implant 4405 and surface 4415 is sculptedto match/complement for bonding or surface 4415 is sculpted and surface4410 is thereafter formed to match/complement surface 4415. Anadditive/subtractive manufacturing process may be used to make surface4410 and/or implant 4405. For example, implant 4405 may include twoportions—a premade head portion and a later-formed body portion that maybe contoured or manufactured as needed to produce surface 4410, with thehead portion and body portion joined together to produce implant 4405

Bone ingrowth technology has not enjoyed that same success in shoulderand knee replacement surgery as it has done in hip replacement surgery.One reason that this may be true is because current methods do not allowprecise and uniform preparation of bone due to variable density of bone,and especially on the flat surfaces. The ultrasonic assisted bonepreparation (example, the orthopedic sculpting system or smart toolrobot) discussed herein has a potential to solve this problem ofinconsistent bone preparation. The use of the above bone preparationmethod/tools instead of the standard techniques may represent adisruptive technology. The ability to quickly machine bone, and to do itin an extremely precise and safe manner may eliminate the need for bonecement in joint replacement surgery. This fact can cause an explosion inthe use of porous ingrowth prosthesis/technology in orthopedics jointreplacement surgery.

FIG. 45 illustrates a diagram of a smart tool robot 4500 which mayinclude a type of three-dimensional bone processing tool. Robot 4500includes a local controller 4505 coupled to a linkage 4510 which iscoupled to a high-efficiency bone processing tool 4515, with tool 4515including a bone interface implement 4520. Controller 4505 includessystems and methods for establishing and monitoring a three-dimensionalspatial location for implement 4520. Controller 4505 further includesgovernance systems for linkage 4510. Collectively controller 4505 andlinkage 4510 may be a type of constraint, other systems and methods foranother type of constraint and providing feedback may be included insome embodiments of the present invention. Linkage 4510 may include aset of sensors for a set of parameters (e.g., navigational, positional,location, force, and the like) and controller 4505 may include systemsto access and read the set of parameters from linkage 4510.Alternatively, or in addition, controller 4505 may include a set ofsensors producing a set of parameters. In some implementations, theset(s) of parameters may include information regarding forces, location,orientation, and motion of tool 4515 and/or implement 4520. In someembodiments, these set(s) of parameters may include information and datarelative to a portion of bone 4525 that is to be processed usinginterface 4520 of tool 4515. Controller 4505 is secured, constrained,and/or fixed to portion of bone 4525. In some cases, controller 4505 maybe optional and linkage 4510 may be secured, constrained, and/or fixedto portion of bone 4525. Any sensors or functions associated withcontroller 4505 may be omitted and/or distributed among linkage 4510and/or tool 4515 and/or interface 4520.

Linkage 4510, illustrated as including a mechanically limitedarticulating arm, is coupled to both optional controller 4505 and tool4515 (or to portion of bone 4525). In some cases when processing aparticular in-patient bone, controller 4505 may predefine a set of boneregions of the in-patient bone for a processing (e.g., a cutting, aremoving, a reaming, a sawing, a broaching, a burring, implanting andthe like). Controller 4505 may monitor a relative location of interface4520 relative to a particular portion of the in-patient bone to beprocessed and compare that particular portion with the predefinedregions. Those predefined regions may include a first subset of regionsto be processed by interface 4520 and in some cases also include (oralternatively substitute for the first subset) a second subset ofregions not to be processed by interface 4520. Controller 4505 providesa realtime feedback to the user regarding an appropriateness ordesirability of processing each the particular portion of bone at thelocation of interface 4520.

In some cases, the realtime feedback may include a realtime hapticsignal imparted from controller 4505 through linkage 4510 to tool 4515.That haptic signal may be of sufficient strength to significantlyrestrict an ability of an operator to casually move interface 4520 to aregion of the in-patient bone that is not to be processed, and somecases may essentially prevent or inhibit the locating of interface 4520to those regions of the in-patient that are not to be processed.

Other feedback signals may be included in addition, or in lieu of, thehaptic system. Audio feedback may in some cases be sufficient to providefeedback to an operator.

Tool 4515 may be an embodiment of an ultrasonically enhanced bonepreparation tool which operates interface 4520. Tool 4515 includes amotive system that operates interface 4520 with a bone processingmotion. The bone processing motion includes a primary motion having aprimary freedom of motion (e.g., for a burr as illustrated, the primarymotion may include a rotation about a longitudinal axis, this primarymotion having a freedom of motion that includes the rotation about thelongitudinal axis). The bone processing motion includes a secondarymotion having a secondary freedom of motion, the secondary freedom ofmotion different from the first freedom of motion. The secondary motionincludes an ultrasonic vibratory motion that enhances thebone-preparation of interface 4520 than would be the case of the primarymotion alone. Other tools may include tools for preparation of implantsite in portion of bone 4525 and/or installation of an implant intoportion of bone 4525 and/or repositioning of a mal-positioned implantinstalled into portion of bone 4525.

Different implements and tools may include varying primary and secondarymotions, there generally being six freedom of motion possibilities forthe primary or secondary motions: x, y, and z translations and rotationsabout any of the x, y, and z axes. Typically the primary motion willinclude a repetitive (and sometimes reciprocating) component.

An operator grips tool 4515 and manipulates it by hand. Controller 4505automatically monitors these manipulations to establish a relativelocation of interface 4520 with respect to a particular portion of anin-patient bone. Comparison of the relative location topredetermined/premapped regions of the in-patient bone that identifyprocessable/non-processable regions results in controller 4505 is usedto provide appropriate realtime feedback signals to the operator foreach particular portion of bone.

FIG. 46-FIG. 49 illustrate an alternative implementation of a mechanicalalignment system similar to that described herein in connection withprosthetic body 2100 and clamp 3300, including the followingdifferences. FIG. 46 illustrates a side view of an alternativeprosthetic body 4600 to be mechanically joined to an installableprosthetic head (e.g., head 2200), FIG. 47 illustrates a top view ofalternative prosthetic body 4600 and FIG. 48 illustrates an enlargedfront view of alternative prosthetic body 4600.

Body 4600 includes stem portion 2105 for insertion into a prepared boneand taper portion 2110 for mechanical joinder to a selected installableprosthetic head. Center line 2115 is defined as a central axis of taperportion 2110. Taper portion 2110 may include a two-dimensional symmetryalong a length of center line 2115. The installable prosthetic head willinclude a complementary taper cavity that may further match thistwo-dimensional symmetry over a depth of the taper cavity along a tapercavity center line. Maintaining an alignment of these center lines asthe prosthetic head is mechanically joined to taper portion 2110 mayreduce, minimize, and/or eliminate canting or dangerous installationconditions that may contribute to or exacerbate any trunnionosis relatedto assembly of the prosthetic head onto taper portion 2110. Body 2100may include, as a grip structure, a non-traditional engagement element4605 centered on center line 2115 proximate taper portion 2110.

Element 4605 includes a protrusion or an indentation into body 4600.Body 4600 may include one element 4605 on opposite sides. Theseelement(s) 4605 may be the same (i.e., both protruding or indented) orthey may be different (one protruding and one indenting). These gripstructures are complementary to a mating grip structure on an engagementclamp used to join the installable head onto taper 2110. Element(s) 4605is non-planar with surrounding portions of body 4600 (i.e., it extendsor retracts relative to the surrounding portion) and is not a completeaperture/hole through body 4600.

Element 4605 includes a perimeter profile (illustrated in FIG. 46 as anequilateral triangle centered on centerline 2115 but may be an irregularor other regular triangle such as an isosceles triangle or the like).That profile may be any non-circular shape and in a special case, theprofile may be circular in an event that elements on opposite side arenot co-axial on centerline 2115 (e.g., one element 4605 is centered oncenterline 2115 somewhat closer to taper 2110 than the other element4605 on the opposite side of body 4600). The profile may include aregular or irregular polygon of N number of sides, Nε{3, 4, 5, 6, 7, 8,9, 10, or more}, and may include an appropriate positive or negativedove tail on lateral portions of one or more walls as described herein,or other regular or irregular non-circular perimeter, or circularperimeters when opposing structures are not co-axial (all representativeof structures preventing, inhibiting, and/or resisting having these gripstructures act as an axle and allow rotation of the clamp out ofcenterline alignment(s).

In some embodiments, there may be particular arrangements or additionalconsiderations for element 4605. As noted herein, a compatible clampincludes an engagement system compatible with element(s) 4605 which maybe designed to mechanically join an installable prosthetic head ontotaper 2110. This will include an application of force and it may bedesirable to improve an interlocking interaction of such a compatibleclamp and body 4600.

One way that this interlocking interaction may be improved is to providedove tails on one or more engaging surfaces. Another way is forconsideration of an orientation of element 4605.

FIG. 47 and FIG. 48 illustrate a dove tail 4705 on an extending wallwhen elements 4605 include a protruding element 4605. Further, asillustrated in FIG. 46, element(s) 4605 have a vertex of the equilateraltriangle that is further away from taper 2110 aligned on centerline. Insome embodiments, it may be preferred that dove tail 4705 is at anegative angle (an angle between an outermost surface and the extendingwall is less than ninety degrees as illustrated in FIG. 47 and FIG. 48).For example, an angle may be less than fifteen degrees, preferably lessthan ten degrees, and in some embodiments about seven degrees. In someembodiments, a mating engagement structure for extending element 4605 ona compatible clamp may include a complementary cavity. Thatcomplementary cavity may include a positive dove tail.

A dove tail on a cavity wall when element 4605 includes an indentingelement 4605 may also be provided—however in such cases it may bedesirable to reorient the equilateral triangle so that one vertex isclosest to taper 2110 and lies on centerline 2115. An embodimentincluding this arrangement may include indenting element 4605 generallyequivalent to the complementary cavity described herein with the matingengagement structure of the compatible clamp including a complementaryextending structure. The indenting element 4605 may thus have a positiveangle dove tail and the mating engagement structure the negative dovetail, including the range of angles as described herein.

These dove tails help to create a locking interface between body 4600and the compatible clamp as the aligned body and clamp force the headonto taper 2110. This locking interface helps to further resistrotations of the clamp relative to body 4600, among other potentialadvantages (in addition to the perimeter profile shapes and relativepositioning of element(s) 4605).

FIG. 49 illustrates an alternative clamp 4900 for use with prostheticbody 4600 of FIG. 46. As illustrated, clamp 4900 defines an assembly(some embodiments may include a unitary design) having a first arm 4905and a second arm 4910 that may be joined to first arm 4905 and form agenerally U-shaped structure.

First arm 4905 includes a first mating engagement structure 4915 andsecond arm 4910 includes a second mating engagement structure 4920.These structures are compatible and complementary to the appropriategrip structures (including element(s) 4605)) on body 4600. As notedherein, when the grip structures include an extending element, thecorresponding compatible and complementary mating engagement structuremay include a conforming cavity. When the grip structures include anindenting element, the corresponding compatible and complementary matingengagement structure may include an extending structure. Depths,perimeter shapes, and other mechanical coupling parameters arecompatible for corresponding element and mating structures.

Clamp 4900 includes a clamp centerline 4925 that is designed to beco-axial with centerline 2115 of body 4600. In some embodimentsdescribed herein, engagement systems may have included an adapter tomaintain an axis of the installable head aligned with these centerlines.

Some embodiments may not include this optional adapter. For example, insome instances, installable head may be “self-centering” such that anapplication of the aligned assembly forces by the alignment of thecenterlines during installation causes installable head to automaticallyalign and achieve the desired orientation relative to body 4600. Thussome embodiments may include, and some embodiments may exclude, such anadapter for the installable head.

FIG. 50-FIG. 51 illustrate an embodiment of an enhancement to theassembly systems described herein. An embodiment may provide a surgeonwith a solution to assure a proper environment (e.g., dry) for the taperassembly. FIG. 50-FIG. 52 illustrate and inclusion of tubes, channels,or the like in or in association with one or more components of theassembly device, for example the clamp, head holder, or other structure,to provide a steady flow of fluid (i.e., gas) to keep the trunnion headtaper interface dry and free of contaminants during the taper impactionprocess. During actual assembly in an operating room environment, it issometimes necessary or desirable to remove fluids from the insides ofvarious cavities, such as a cavity of the installable head designed tobe mounted to taper 2110. One modality of removing fluids from a cavityis to direct a stream of a safe fluid (e.g., carbon dioxide gas, ambientair, or other gas) into the cavity. The fluid may include a gasexclusively when the desired environment is to dry out the cavity. Insome applications, a special liquid (e.g., saline solution or the like)may be desirable when the environment need not be dry, particularly whenthe liquid may facilitate the mechanical joinder and not adverselyaffect the patient/procedure.

The embodiments described herein may include one or more discrete orintegrated channels having outlet jets directed to the installable headcavity to automatically purge fluid from inside the cavity duringassembly of the head onto the taper such as when force is being appliedto the prosthesis body and installable head to join them together.

FIG. 50 illustrates a generic fluid injection system 5000 for use with amodular assembly tool 5005, examples of which are described herein. Tool5005 mechanically joins installable head 5010 to prosthesis body 5015 byvarious force application and transfer modalities. For example, tool5005 may include a force generator 5020 coupled to a force applicator5025 that coaxially applies joinder forces to head 5010 to assemble head5010 onto body 5015. As noted herein, tool 5005 may include an optionalhead holder 5030 to further aid in alignment of the various relevantaxes (e.g., force application, body, and head).

In some instances, body 5015 is installed into living bone first andthen head 5010 is joined onto body 5015. There may be variouscontaminants present during this joining process which may interferewith assembly, joinder, cold-welding, and the like. It may be desirableto aid the surgeon in assembly and improve a quality of the final resultby purging the contaminants from the cavity, taper, and the like duringthe assembly process.

An embodiment of the present invention may include use of a fluid jetsystem that includes a reservoir 5035 for holding a desired purgingfluid, one or more channels, tubes, conveyance structures, and otherdevices 5040 for communicating the desired purging fluid to thecavity/taper area, and a nozzle, aperture, or jet 5045 proximate thecavity/taper during assembly to direct the desired purging fluid to theappropriate locations.

FIG. 51 illustrates a fluid jet system 5100 directing a fluid 5105(e.g., a gas) into a cavity 5110 of the installable prosthetic head5115. An irrigation system for providing fluid 5105 may be implementedin several ways, including a pressurized fluid reservoir 5120 includingthe irrigating fluid 5105, a valve 5125 controlling a flow of fluid 5105in one or more channels 5130, each channel may terminate in a nozzle5135 directed towards head 5115.

Preferably one or more channels 5130 are coupled to and/or integratedwith one or more arms of the clamp. Valve 5125 may be manually operatedor automatically synchronized with application of an installation forceto head 5115.

FIG. 52 illustrates an alternative fluid jet system 5200 for directingfluid 5105 into cavity 5110 of installable prosthetic head 5115. System5200, similar to system 5100, illustrates an alternative irrigationsystem for use when optional adapter 5205 is used to secure and alignhead 5115 to the centerlines. In addition, or in lieu of, channels 5130being coupled to the clamp, one or more channels 5130 may be coupled toadapter 5205. In practice these may be very small channels or adaptersand there may be many ways to provide the fluid directing channels andnozzles to maintain a desired stream of desired fluid into cavity 5110during assembly of head 5115 onto taper 2110.

In addition to the use of a fluid, FIG. 50 also illustrates use of arealtime interface-force evaluation system. This evaluation system usesa first force F1 (which may be measured or known a priori) from forceapplicator 5020 and transfers that to a joinder force that assembleshead 5010 onto body 5015. Forcer applicator 5025 evaluates interfaceparameters (which may include measurement of force, velocity,acceleration of one or more interface elements or combinations of suchelements), such as a magnitude of a second force F2 and compares that tothe first force F1—it may further include first and second derivativesrelated to interface element motions and accelerations, andcharacterizations of a response of head/body to the first force. In somecases, among other uses, the realtime interface-force evaluation systemenables an operator to understand when the head/body interface hasproduced a cold weld. For example, this may be indicated when F2 iswithin a predetermined threshold of F1. There may be many different waysto implement such an evaluation system, for example, U.S. patentapplication Ser. No. ______(Attorney Docket No. 20326-7052 filed on thesame date as this application) further discusses details of a realtimeinterface-force system which may be used for this purpose, the contentsof this patent application are hereby expressly incorporated byreference thereto in their entireties for all purposes.

Further, such a realtime interface-force evaluation system mayadvantageously be used with smart tool robot 4500, e.g., a 3D sculptor,an ultrasonic machining tool, robotic tool, or the like, in whichrealtime response evaluations of a processing element, for exampleduring operation on bone or other tissue, to applied force(s) may allowadditional insight into the bone or tissue. For example, this additionalinsight may inform subsequent processing, such as installation of animplant, an elasticity constant of the bone/tissue, a recommended oroptimum size of the implant relative to the installation site, or otherinformation. The incorporated Patent Application filed on the same dayreferenced herein further discusses details of a realtimeinterface-force system which may be used for this purpose.

The system and methods above has been described in general terms as anaid to understanding details of preferred embodiments of the presentinvention. In the description herein, numerous specific details areprovided, such as examples of components and/or methods, to provide athorough understanding of embodiments of the present invention. Somefeatures and benefits of the present invention are realized in suchmodes and are not required in every case. One skilled in the relevantart will recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, methods, components, materials, parts,and/or the like. In other instances, well-known structures, materials,or operations are not specifically shown or described in detail to avoidobscuring aspects of embodiments of the present invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Combinations of components or steps will also beconsidered as being noted, where terminology is foreseen as renderingthe ability to separate or combine is unclear.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the Abstract, is not intendedto be exhaustive or to limit the invention to the precise formsdisclosed herein. While specific embodiments of, and examples for, theinvention are described herein for illustrative purposes only, variousequivalent modifications are possible within the spirit and scope of thepresent invention, as those skilled in the relevant art will recognizeand appreciate. As indicated, these modifications may be made to thepresent invention in light of the foregoing description of illustratedembodiments of the present invention and are to be included within thespirit and scope of the present invention.

Thus, while the present invention has been described herein withreference to particular embodiments thereof, a latitude of modification,various changes and substitutions are intended in the foregoingdisclosures, and it will be appreciated that in some instances somefeatures of embodiments of the invention will be employed without acorresponding use of other features without departing from the scope andspirit of the invention as set forth. Therefore, many modifications maybe made to adapt a particular situation or material to the essentialscope and spirit of the present invention. It is intended that theinvention not be limited to the particular terms used in followingclaims and/or to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include any and all embodiments and equivalents falling within thescope of the appended claims. Thus, the scope of the invention is to bedetermined solely by the appended claims.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A modular prosthesis body, comprising: a stemportion; a trunnion portion coupled to said stem portion, said trunnionportion having an insertion profile defining an insertion axis andfurther defining a pair of opposing side faces including a first sideface and a second side face; a first grip structure coupled to saidfirst side face and disposed on said insertion axis; and a second gripstructure coupled to said second side face and disposed on saidinsertion axis.
 2. The modular prosthesis body of claim 1 wherein saidtrunnion portion includes a trunnion taper symmetric about saidinsertion axis.
 3. The modular prosthesis body of claim 1 wherein saidgrip structures each include an extending engagement element.
 4. Themodular prosthesis body of claim 1 wherein said grip structures eachinclude an indenting engagement element.
 5. The modular prosthesis ofclaim 1 wherein said grip structures each include a non-circularexterior perimeter.
 6. The modular prosthesis of claim 1 wherein saidgrip structures each include a triangle exterior perimeter centered onsaid insertion axis wherein a vertex of said triangle exterior perimeteris disposed on insertion axis.
 7. The modular prosthesis of claim 3wherein said grip structures each include a triangle exterior perimetercentered on said insertion axis wherein a vertex of said triangleexterior perimeter is disposed on insertion axis.
 8. The modularprosthesis of claim 4 wherein said grip structures each include atriangle exterior perimeter centered on said insertion axis wherein avertex of said triangle exterior perimeter is disposed on insertionaxis.
 9. The modular prosthesis of claim 1 wherein a lateral wall ofeach said grip structure includes a dove tail.
 10. The modularprosthesis of claim 3 wherein a lateral wall of each said grip structureincludes a dove tail.
 11. The modular prosthesis of claim 4 wherein alateral wall of each said grip structure includes a dove tail.
 12. Themodular prosthesis of claim 5 wherein a lateral wall of each said gripstructure includes a dove tail.
 13. The modular prosthesis of claim 6wherein a lateral wall of each said grip structure includes a dove tail.14. The modular prosthesis of claim 7 wherein a lateral wall of eachsaid grip structure includes a dove tail.
 15. The modular prosthesis ofclaim 8 wherein a lateral wall of each said grip structure includes adove tail.
 16. A system for assembly of a modular prosthesis including astem portion, a trunnion portion coupled to the stem portion, thetrunnion portion having an insertion profile defining an insertion axisand a pair of opposing side faces defining a non-planar grip structure,and a prosthesis head configured to be installed on the trunnion portionand defining an installation aperture complementary to said insertionprofile with the installation aperture defining an installation axis,comprising: a head grasper including a housing defining a cavitycomplementary to an outer portion of the prosthesis head with saidhousing having a grasper axis extending through said cavity wherein saidhousing is configured to secure the prosthesis head within said cavityand align said grasper axis with the installation axis; wherein saidhead grasper includes a pair of mating engagement structures,complementary to the grip structures, for non-rotatingly securement ofsaid head grasper to the trunnion portion.
 17. The system of claim 16further comprising: a tool, coupled to said head grasper, generating anassembly force aligned with said grasper axis.
 18. The system of claim17 wherein said tool includes a shaft coupling said head grasper andwherein said shaft includes a force sensing arrangement.
 19. The systemof claim 18 wherein said tool includes a force engine producing saidassembly force.
 20. The system of claim 19 wherein said force engineincludes a torquer generating a torque and a converter coupled to saidtorque producing a decreasing displacement, responsive to said torque,of the prosthesis head relative to the stem.
 21. The system of claim 19wherein said force engine includes an impulser generating a set ofimpulses and a converter coupled to said set of impulses producing adecreasing linear displacement, responsive to said motion, of theprosthesis head relative to the stem.
 22. The system of claim 19 whereinsaid force engine includes a motor generating a motion and a convertercoupled to said motion producing a decreasing linear displacement,responsive to said motion, of the prosthesis head relative to the stem.23. The system of claim 16 further comprising a fluid ejection system,coupled to said head grasper, configured to direct a fluid into theinstallation aperture.
 24. The system of claim 23 wherein said fluidconsists essentially of an inert gas.
 25. An apparatus for assembly of amodular prosthesis including a stem portion, a trunnion portion coupledto the stem portion, the trunnion portion having an insertion profiledefining an insertion axis and a pair of opposing side faces defining anon-planar grip structure, and a prosthesis head configured to beinstalled on the trunnion portion and defining an installation aperturecomplementary to said insertion profile with the installation aperturedefining an installation axis, comprising: a clamp including a pair ofmating engagement structures, complementary to the grip structures, fornon-rotatingly securement of the prosthesis head to the trunnionportion, said clamp including a force applicator configured to apply arelative assembly force between the trunnion portion and to theprosthesis head to install the prosthesis head on the trunnion portionwherein said clamp aligns the axes and wherein said relative assemblyforce is constrained by said clamp to be coaxial with the axes.
 26. Thesystem of claim 25 further comprising a fluid ejection system, coupledto said clamp, configured to direct a fluid into the installationaperture.
 27. The system of claim 26 wherein said fluid consistsessentially of an inert gas.